Patterns Of Locoregional Failure Research Articles

Differences in geometric patterns of failure in human papillomavirus (HPV)-associated and HPV-non-associated oropharyngeal cancer after definitive radiotherapy.

The aim of this study was to evaluate and compare the spatial pattern of locoregional recurrences in patients diagnosed with HPV-associated and HPV-non-associated oropharyngeal SCC (OPSCC) treated with definitive radiotherapy. Patients who had locoregional recurrence following definitive intensity-modulated radiation therapy were identified at a single tertiary institution. Target volumes were delineated according to the latest consensus international guidelines. Recurrences were classified into five categories based on radiotherapy dose distribution and target volume, using a previously validated methodology; type A (central high dose), type B (peripheral high dose), type C (central elective dose), type D (peripheral elective dose), and type E (extraneous dose). The types of failure were compared between p16-positive and p16-negative tumors using the Pearson chi-square test. Fifty-eight locoregional recurrences were observed in 36 patients. The majority of recurrences were in nodal locations (66%, 38/58). Among these, 34 (59%) were classified as type A, 6 (10%) as type B, 9 (15%) as type C, 5 (9%) as type D, and 4 (7%) as type E failure. A significant difference was found in the types of failure between p16-positive and p16-negative tumors (X2 9.52, p = 0.044). p16-negative tumors were more likely to have recurrences in a peripheral location compared to p16-positive tumors (32% vs. 7%). p16-positive tumor were more likely to have extraneous recurrences (17% vs. 0%). Our study results identified a significant difference in patterns of locoregional failure among patients diagnosed with oropharyngeal cancer following consensus-based tumor delineation and modern radiotherapy. Further confirmatory pattern of failure studies are required to enable greater individualization of radiotherapy for patients diagnosed with oropharyngeal malignancy in the future.

Outcomes among oropharyngeal and oral cavity cancer patients treated with postoperative volumetric modulated arctherapy.

Presently, there are few published reports on postoperative radiation therapy for oropharyngeal and oral cavity cancers treated with IMRT/VMAT technique. This study aimed to assess the oncological outcomes of this population treated with postoperative VMAT in our institution, with a focus on loco-regional patterns of failure. Between 2011 and 2019, 167 patients were included (40% of oropharyngeal cancers, and 60% of oral cavity cancers). The median age was 60 years. There was 64.2% of stage IV cancers. All patients had both T and N surgery. 34% had a R1 margin, 42% had perineural invasion. 72% had a positive neck dissection and 42% extranodal extension (ENE). All patients were treated with VMAT with simultaneous integrated boost with three dose levels: 66Gy in case of R1 margin and/or ENE, 59.4-60Gy on the tumor bed, and 54Gy on the prophylactic areas. Concomittant cisplatin was administrated concomitantly when feasible in case of R1 and/or ENE. The 1- and 2-year loco-regional control rates were 88.6% and 85.6% respectively. Higher tumor stage (T3/T4), the presence of PNI, and time from surgery >45 days were significant predictive factors of worse loco-regional control in multivariate analysis (p=0.02, p=0.04, and p=0.02). There were 17 local recurrences: 11 (64%) were considered as infield, 4 (24%) as marginal, and 2 (12%) as outfield. There were 9 regional recurrences only, 8 (89%) were considered as infield, and 1 (11%) as outfield. The 1- and 2-year disease-free survival (DFS) rates were 78.9% and 71.8% respectively. The 1- and 2-year overall survival (OS) rates were 88.6% and 80% respectively. Higher tumor stage (T3/T4) and the presence of ENE were the two prognostic factors significantly associated with worse DFS and OS in multivariate analysis. Our outcomes for postoperative VMAT for oral cavity and oropharyngeal cancers are encouraging, with high rates of loco-regional control. However, the management of ENE still seems challenging.

Patterns of Locoregional Failure After Ablative 5-Fraction Stereotactic MR-Guided on-Table Adaptive Radiation Therapy for Pancreatic Cancer

SBRT for pancreatic ductal adenocarcinoma (PDAC) is routinely delivered with non-ablative dose to only gross disease resulting in locoregional failure (LRF) rates of >50%, most commonly near the celiac artery (CA) and/or superior mesenteric artery (SMA). It is unclear whether an alternative approach of prescribing ablative dose to gross disease plus elective coverage prevents and/or delays LRF. The study objective was to describe the incidence and anatomic distribution of LRF using this treatment approach. A single institution retrospective analysis was performed of non-metastatic PDAC patients who received ablative stereotactic MR-guided on-table adaptive radiation therapy (A-SMART) on a 0.35T MR-Linac from 2018-2022. Median prescribed dose was 50 Gy/5 fractions. Elective coverage (EC), including a margin around the primary tumor, CA, and SMA, to 33-35 Gy/5 fractions became routine in 2019 using a simultaneous integrated boost; the porta hepatis was not routinely covered. LRFs were contoured and defined as out-of-field (OOF), marginal (M), or in-field (IF) if >80%, 20-80%, or <20% of it was outside of the most peripheral prescription isodose line. One hundred four patients were evaluated (87% head tumors). 94% had induction chemotherapy (median 4 months), usually FOLFIRINOX (66%) or gemcitabine/nab-paclitaxel (27%). 88% received EC. Median GTV, CTV, PTVgrosstumor, and PTVelective volumes were 29 cc, 90 cc, 64 cc, and 127 cc, respectively. 16 patients (15%) had LRF after a median of 17 months (range: 2.4-30.8) from A-SMART; 13 had scans available for delineating LRF. Median follow-up from A-SMART for the entire cohort vs. LRF was 12 vs. 24 months. LRF involved the primary tumor (31%), retroperitoneal lymph nodes (25%), SMA (19%), porta hepatis (19%), and CA (6%). LRF was OOF, M, or IF in 30.8% (n = 4), 61.5% (n = 8), and 7.7% (n = 1). Distance from the 3 SMA failures to SMA origin was 10 cm (EC used), 9.3 cm (EC used), and 3 cm (no EC). The 1 CA failure involved the CA origin (no EC). Median mean, maximum, and minimum dose of the contoured LRF region on the original plan was 33.3 Gy (range: 9.7-50.3 Gy), 56 Gy (range: 44.2-71.4 Gy), and 11.4 Gy (range: 1.2-22.7 Gy), respectively. Median V20, V25, V30, V35, and V40 of the contoured LRF was 84.3% (range: 16.1-100%), 69.2% (range: 12.5-99.7%), 57.5% (range: 9.3-95.5%), 41.2% (range: 6.8-84.0%), and 32.7% (range: 4.8-71.8%). This study represents the first patterns of LRF analysis after ablative 5-fraction SBRT for PDAC. Although EC is not currently endorsed by published pancreas SBRT guidelines, our low LRF incidence especially involving the CA/SMA demonstrates that EC should be considered, even when delivering ablative dose. Furthermore, given that nearly all LRF were M or OOF we have considered expanding our institutional elective volumes. While the optimal EC dose is uncertain, 33-35 Gy appears effective in limiting IF LRF and therefore has been standardized within ongoing ablative SBRT trials for PDAC at our institution.

Analysis of the Cancer Imaging Archive for Patterns of Locoregional Failure in Relation to the Mucous Membranes among Patients with Head and Neck Squamous Cell Carcinoma: Potential Organ at Risk that can be Spared?

Radiation-induced oral mucositis (RIOM), a painful inflammation and ulceration of the mucous membranes (MM), occurs as a common and severe side effect of radiation treatment (RT) for head and neck cancers. It worsens significant quality of life leading to treatment interruption or cancellation. In RIOM, radiation injury of the MM basal epithelial cells may be one of the critical pathophysiological mechanisms. However, it is unclear if advanced radiation treatments could spare MM, without compromise on tumor control. The purpose of this study is to determine whether the MM that do not overlap with the prescription target volumes are a common site of locoregional recurrence in head and neck cancers. A de-identified data collection of 215 head and neck cancer patients stored within The Cancer Imaging Archive was downloaded for analysis. Imaging series both before and after RT were downloaded, as well as RT structures and RT dosimetric data. Diagnostic CECT and/or PET/CT and/or MRI scans documenting the initial evidence of recurrence were co-registered with corresponding original planning CTs. Radiologically evident recurrent gross disease (rGTV) was manually contoured, as well as the MM (defined as an approximately 3mm thick wall of mucosa tissue lining the oral cavity and pharynx and excluding any overlap with the radiation prescription targets). Contoured MM structures were cross-referenced with the sites of recurrence by examining the overlap of the MM volumes with the rGTV volumes. A total of 40 patients had documented evidence of recurrence; 38 of which had images available for analysis. Overall, 23 (60.5%) were oropharynx cancer. Of the 38 recurrences, 35 (92%) were locoregional: 23 with only local (60.5%) recurrences, 9 with only regional (23.7%) recurrences and 3 (7.9%) with both local and regional recurrences. One patient (2.6%) had distant recurrence, one patient had both regional and distant recurrences concomitantly, and one patient had local, regional and distant recurrences simultaneously. Overall, 30 patients (78.9%) had recurrences located exclusively within prescription PTV volumes/isodose lines. Four patients (10.5%) had recurrences located outside prescription PTV volumes/isodose lines, four patients (10.5%) had recurrences located both within and outside prescription PTV volumes/isodose lines (i.e., 2 sites of concomitant recurrence). Importantly, 0 patients (0%) had recurrences located in the contoured MM (excluding any overlap with the radiation prescription targets). Based on this retrospective series, the MM (excluding the areas of overlap with radiation prescription targets) are a rare location of locoregional recurrence. Hence, sparing the MM using radiation advanced dosimetry techniques could be a reasonable approach to reducing the incidence/severity of radiation-induced oral mucositis, without compromising tumor control. However, this requires further prospective investigation.

Locoregional Failure During and After Short-course Radiotherapy Followed by Chemotherapy and Surgery Compared With Long-course Chemoradiotherapy and Surgery: A 5-Year Follow-up of the RAPIDO Trial.

To analyze risk and patterns of locoregional failure (LRF) in patients of the RAPIDO trial at 5 years. Multimodality treatment improves local control in rectal cancer. Total neoadjuvant treatment (TNT) aims to improve systemic control while local control is maintained. At 3 years, LRF rate was comparable between TNT and chemoradiotherapy in the RAPIDO trial. A total of 920 patients were randomized between an experimental (EXP, short-course radiotherapy, chemotherapy, and surgery) and a standard-care group (STD, chemoradiotherapy, surgery, and optional postoperative chemotherapy). LRFs, including early LRF (no resection except for organ preservation/R2 resection) and locoregional recurrence (LRR) after an R0/R1 resection, were analyzed. Totally, 460 EXP and 446 STD patients were eligible. At 5.6 years (median follow-up), LRF was detected in 54/460 (12%) and 36/446 (8%) patients in the EXP and STD groups, respectively ( P =0.07), in which EXP patients were more often treated with 3-dimensional-conformed radiotherapy ( P =0.029). In the EXP group, LRR was detected more often [44/431 (10%) vs. 26/428 (6%); P =0.027], with more often a breached mesorectum (9/44 (21%) vs. 1/26 (4); P =0.048). The EXP treatment, enlarged lateral lymph nodes, positive circumferential resection margin, tumor deposits, and node positivity at pathology were the significant predictors for developing LRR. Location of the LRRs was similar between groups. Overall survival after LRF was comparable [hazard ratio: 0.76 (95% CI, 0.46-1.26); P =0.29]. The EXP treatment was associated with an increased risk of LRR, whereas the reduction in disease-related treatment failure and distant metastases remained after 5 years. Further refinement of the TNT in rectal cancer is mandated.

Pattern of locoregional failure in postoperative cases of locally advanced carcinoma of buccal mucosa treated with unilateral versus bilateral neck radiation: lesson learned from a basic practice setup.

Carcinoma of buccal mucosa forms a sizeable percentage of the diagnosed oral cavity cancers in India. There is limited data on elective treatment of the contralateral neck for well-lateralized carcinoma with no involved nodes in the contralateral neck. We conducted this study to compare locoregional control in patients treated with unilateral vs. bilateral neck irradiation. 48 patients with carcinoma of buccal mucosa were selected. Patients were divided into unilateral and bilateral arms based on radiation treatment of the ipsilateral or bilateral neck. All patients received adjuvant radiation with Cobalt 60 unit. Patient-specific and follow-up data were collected from records and dosimetric data from treatment planning system (TPS). Chi-square and unpaired t-test was used to compare data between arms and Kaplan Meier plot; Cox regression was used for survival analysis. After a median follow-up of 23 months, 15 (31.3%) patients had developed disease recurrence, 8 and 7 in the unilateral and bilateral arms, respectively (p = 0.591). There was no contralateral neck failure during the follow-up period. The 2-year disease-free survival was 68.2% and 72.2% in the unilateral and bilateral arms, respectively. Among risk factors for disease recurrence, depth of invasion (DOI), delay in starting radiation and planning target volume (PTV) coverage were significant contributing factors. Cox multivariate regression suggested DOI and delay in starting radiation to be significant prognostic factors for disease-free survival (DFS). Bilateral neck radiation does not provide any advantage over ipsilateral neck radiation for properly selected well lateralized buccal mucosal squamous cell carcinoma. Ipsilateral neck radiation facilitates better sparing of organs at risk.

Detailed analysis of failure patterns using deformable image registration in hypopharyngeal cancer patients treated with sequential boost intensity-modulated radiotherapy.

Sequential boost intensity-modulated radiotherapy (SQB-IMRT) uses two different planning CTs (pCTs) and treatment plans. SQB-IMRT is a form of adaptive radiotherapy that allows for responses to changes in the shape of the tumour and organs at risk (OAR). On the other hand, dose accumulation with the two plans can be difficult to evaluate. The purpose of this study was to analyse patterns of loco-regional failure using deformable image registration (DIR) in hypopharyngeal cancer patients treated with SQB-IMRT. Between 2013 and 2019, 102 patients with hypopharyngeal cancer were treated with definitive SQB-IMRT at our institution. Dose accumulation with the 1st and 2nd plans was performed, and the dose to the loco-regional recurrent tumour volume was calculated using the DIR workflow. Failure was classified as follows: (i) in-field (≥95% of the recurrent tumour volume received 95% of the prescribed dose); (ii) marginal (20-95%); or (iii) out-of-field (<20%). After a median follow-up period of 25months, loco-regional failure occurred in 34 patients. Dose-volume histogram analysis showed that all loco-regional failures occurred in the field within 95% of the prescribed dose, with no marginal or out-of-field recurrences observed. The dosimetric analysis using DIR showed that all loco-regional failures were within the high-dose region. More aggressive treatment may be required for gross tumours.

Long-Term Outcome Following Intensity-Modulated Radiotherapy Delivered Using Individualized Clinical Target Volume Delineation Based on Stepwise Spread Pattern of Nasopharyngeal Carcinoma

<h3>Purpose/Objective(s)</h3> The optimal method for clinical target volume delineation in nasopharyngeal carcinoma has not yet been determined. We have developed an individualized CTV delineation protocol based on the stepwise spread patterns of NPC. This study aimed to determine the long-term outcomes and toxicities in NPC patients receiving intensity-modulated radiotherapy with individualized CTV delineation. <h3>Materials/Methods</h3> We retrospectively reviewed the data of patients with newly diagnosed nondisseminated NPC who underwent IMRT using our individualized CTV delineation protocol. A total of 7,262 patients with NPC (79.3% patients in stage III-IVA) treated between April 2009 and December 2015 were included in this study. Dose–volume statistics, clinical outcomes, patterns of failures and toxicities were assessed. To analyze dose distribution of patients with or without local recurrence, propensity score matching (PSM) was performed to compare the dose between the two groups matched by age, sex, histological type, T category, N category, chemotherapy and gross tumor volume of primary tumor and enlarged retropharyngeal lymph nodes (GTVnx) in a 1:1 ratio. <h3>Results</h3> Median follow-up was 67.3 (range, 2.0-118.7) months. The 5-year local relapse–free survival, regional relapse–free survival, distant metastasis–free survival, progression–free survival, and overall survival rates were 93.6%, 94.4%, 86.8%, 77.8%, and 86.0%, respectively. In-field failure is the major locoregional failure pattern, accounting for 92.3% patients of local and 86% of regional recurrence. Age and T classification were independent prognostic for LRFS, DMFS, PFS, and OS in multivariate analysis. Late grade 3 toxicities were mild and included ear injury (1.8%), xerostomia (0.2%), dysphagia (0.2%), brain injury (0.2%), and trismus (0.1%). No grade 4 toxicity occurred during IMRT or follow-up. PSM analysis revealed no significant difference between minimum (P = 0.815), maximum (P = 0.595), and mean (P = 0.700) dose to the planning tumor volume of primary tumor and enlarged retropharyngeal lymph nodes (PTVnx) between patients with local recurrence and the matched patients without local recurrence. <h3>Conclusion</h3> Our stepwise CTV delineation protocol appears to be a promising strategy for improving outcomes in NPC.

Patterns of locoregional failure and distant metastases in patients treated for locally advanced rectal cancer in the RAPIDO trial

Background: Optimizing rectal cancer treatment has reduced locoregional failures (LRFs), however, many patients still develop distant metastases (DM). The current study aims to investigate whether a different preoperative treatment strategy influences patterns and development of LRF and DM in patients with high-risk locally advanced rectal cancer (LARC).

Radiotherapy in Breast Cancer Patients With Isolated Regional Recurrence After Mastectomy: A Joint Analysis of 144 Cases From Two Institutions

<h3>Purpose/Objective(s)</h3> To analyze the prognosis and locoregional failure patterns of patients with isolated regional recurrence (RR) after mastectomy and investigate the effect of radiotherapy (RT) and optimal radiation target volumes. <h3>Materials/Methods</h3> A total of 144 patients with first isolated RR after mastectomy treated in two institutions between 2001 and 2018 were retrospectively analyzed. All had not received postmastectomy RT. 100 (69.4%) had supraclavicular fossa (SC) recurrence, 54 (37.5%) had axilla recurrence, and 7(4.9%) had internal mammary region (IM) recurrence. After RR, 93 (63.6%) patients received local plus systemic therapy, 10 (6.9%) received local therapy, and 40 (27.8%) received systemic therapy alone. Among the 103 patients who received local therapy, 27 (26.2%) received surgery plus RT, 60 (58.3%) received RT and 16 (15.5%) received surgery alone. Of the 87 patients who received RT, 14 (16.1%) received involved-field RT, and 73 (83.9%) received additional prophylactic RT to the initially uninvolved locoregional sites. The median dose to the recurrent tumor or tumor bed after surgery was 60 Gy. Of the 73 patients who received prophylactic RT, the median dose was 50 Gy, to chest wall (CW) in 67/87 (77.0%), to SC in 24/28 (85.7%), to axilla in 6/53 (11.3%), and to IM in 3/81 (3.7%). Post-recurrence progression-free survival (PFS) and overall survival (OS) rates were calculated by Kaplan-Meier method and the differences were compared with Log-rank test. Competing risk model was used to estimate the subsequent locoregional recurrence (sLRR) rates, and the differences were compared with Gray test. Multivariate analysis was performed using Cox logistic and Fine–Gray regression. <h3>Results</h3> With a median follow-up of 82.5 months (range, 5.0-205.0) after RR, the 5-year sLRR, PFS and OS rates for the entire group were 42.1%, 22.9% and 62.6%. Local plus systemic therapy was an independent favorable prognostic factor for sLRR and PFS. Surgery plus RT was an independent favorable prognostic factor for sLRR. The most common sLRR sites were initially involved nodal regions, followed by CW, and then initially uninvolved nodal regions. Surgery plus RT significantly reduced the risk of recurrence within the initially involved nodal regions (<i>P</i><0.001). Patients with CW irradiation showed 5-year subsequent CW recurrence rate of 12.1% compared to 14.8% (<i>P</i> = 0.206) for those without. Subsequent SC recurrence rate was numerally lower in patients with prophylactic SC irradiation than those without (9.9% vs. 23.8%, <i>P</i> = 0.206). The incidences of initially uninvolved axillary and IM recurrence were below 10% regardless of prophylactic RT. <h3>Conclusion</h3> Patients with isolated RR after mastectomy have an optimistic OS but a high risk of sLRR after RR in the contemporary era. Comprehensive locoregional treatment including surgery and RT combined with systemic therapy is recommended. The CW, axillary and IM regions should not be routinely included in the radiation target volume.

Patterns of recurrence after surgery and efficacy of salvage therapy after recurrence in patients with thoracic esophageal squamous cell carcinoma

BackgroundInformation on the optimal salvage regimen for recurrent esophageal cancer is scarce. We aimed to assess the patterns of locoregional failure, and evaluate the therapeutic efficacy of salvage therapy along with the prognostic factors in recurrent thoracic esophageal squamous cell carcinoma (TESCC) after radical esophagectomy.MethodsA total of 193 TESCC patients who were diagnosed with recurrence after radical surgery and received salvage treatment at our hospital were retrospectively reviewed from 2004 to 2014. The patterns of the first failure were assessed. The post-recurrence survival rate was determined using the Kaplan-Meier method and analyzed using the log-rank test. Multivariate prognostic analysis was performed using the Cox proportional hazard model.ResultsThe median time of failure was 7.0 months. Among the 193 patients, 163 exhibited isolated locoregional lymph node (LN) recurrence and 30 experienced locoregional LN relapse with hematogenous metastasis. Among the 193 patients, LN recurrence was noted at 302 sites; the most common sites included the supraclavicular (25.8%; 78/302) and mediastinal LNs (44.4%; 134/302), particularly stations 1 to 6 for the mediastinal LNs (36.4%; 110/302). The median overall survival (OS) was 13.1 months after recurrence. In those treated with salvage chemoradiotherapy, with radiotherapy, and without radiotherapy, the 1-year OS rates were 68.5, 55.0, and 28.6%; the 3-year OS rates were 35.4, 23.8, and 2.9%; and the 5-year OS rates were 31.8, 17.2, 2.9%, respectively (P < 0.001). Furthermore, patient survival in those who received salvage chemoradiotherapy was significantly better than those treated with salvage radiotherapy alone (P = 0.044). Multivariate analysis showed that the pathological TNM stage and salvage treatment regimen were independent prognostic factors.ConclusionsSupraclavicular and mediastinal LN failure were the most common types of recurrence after R0 surgery in TESCC patients. Salvage chemoradiotherapy or radiotherapy could significantly improve survival in esophageal cancer with locoregional LN recurrence.

Prognostic factors and patterns of loco-regional failure in patients with R0 resected gallbladder cancer

BackgroundIn this study, risk factors for loco-regional recurrence in curative R0 resected gallbladder adenocarcinoma were investigated. MethodsPatients with gallbladder adenocarcinoma with curative R0 resections between 2000 and 2016 were retrospectively reviewed. Loco-regional failure-free survival (LRFFS) and overall survival (OS) were analyzed using the Kaplan–Meier method; prognostic factors were analyzed using the Cox proportional hazards model. Based on the identified risk factors, patients were grouped for further analysis. ResultsA total of 272 patients were included for analysis; overall, 5-year LRFFS and OS were 83% and 81%, respectively. On multivariate analysis, 3 risk factors for LRFFS were identified; lymphovascular invasion, T3, and N1, by which patients were grouped; group 1 for 0 factor, group 2 for 1 factor and group 3 for 2 to 3 factors. The 5-year LRFFS in groups 1, 2, and 3 were 94%, 73%, and 40%, and the 5-year OS in groups 1, 2, and 3 were 90%, 75%, and 47%, respectively. LRFFS and OS differed significantly among groups (p < 0.05). ConclusionIn patients with R0 resected gallbladder cancer, the presence of >1 risk factor increased the risk of loco-regional recurrence. Additional therapeutic strategy for these patients needs further consideration.

Patterns of locoregional failure in women with early-stage breast cancer treated by whole breast irradiation in the lateral isocentric decubitus position: Large-scale single-centre experience

PurposeThe purpose of this study was to evaluate locoregional control and describe the patterns of failure in patients with breast cancer receiving whole breast radiotherapy in the isocentric lateral decubitus position technique. Patients and methodsIn a series of 832 consecutive female patients with early-stage breast cancer including invasive and in situ tumours treated by breast-conserving surgery followed by three-dimensional conformal whole breast irradiation in the isocentric lateral decubitus position between 2005 and 2010, all patients who experienced locoregional recurrence were studied. Five-year recurrence-free and overall survival rates were calculated. Regional recurrence mapping patterns were also determined. ResultsThe median age of this series of 832 women was 61.5 years (range: 29–90 years). Various types of fractionation were used: 50Gy in 25 fractions (17.9%), 66Gy in 33 fractions (50Gy in 25 fractions to breast followed by sequential boost to tumour bed to a total dose 66Gy in 33 fractions.) (46.5%), 40Gy in 15 fractions or 41.6Gy in 13 fractions (26.1%) and 30Gy in 5 fractions (9.5%). With a median follow-up of 6.4 years, only 36 patients experienced locoregional recurrence and no association with the fractionation regimen was identified (P=0.2). In this population of 36 patients, 28 (3.3%) had “in-breast” local recurrences (77.8%), two had local recurrences and regional lymph node recurrence (5.6%), and six had regional lymph node recurrence only (in non-irradiated areas; 16.6%). The median time to recurrence was 50 months. Complete mapping of patterns of recurrences was performed and, in most cases, local recurrences were situated adjacent to the primary tumour bed. Cases of local recurrences presented a significantly lower distant metastasis rate (P<0.001) and had a significantly longer overall survival compared to patients with regional lymph node recurrence (P<0.001). However, multivariate Cox regression analysis showed that the site of recurrence had no significant impact on overall survival (P=0.14). ConclusionThe results of this study indicate a low local recurrence rate. Further careful follow-up and recording of recurrences is needed to improve the understanding of patterns of recurrence.

Caractérisation des rechutes locorégionales chez des patientes atteintes d’un cancer du sein traité par irradiation pariétale par électrons : expérience monocentrique de l’institut Curie

PurposeThe purpose of this study was to evaluate locoregional control and describe the patterns of locoregional failure in women with breast cancer irradiated by a previously described post-mastectomy highly conformal electron beam radiotherapy technique. Material and methodsWe included all women irradiated by post-mastectomy highly conformal electron beam radiotherapy technique for non-metastatic breast cancer between 2007 and 2011 in our department. All cases of bilateral breast cancer were excluded. All patients who experienced locoregional recurrence have been studied. Mapping patterns of regional recurrences was also performed and compared with the European Society for Radiotherapy and Oncology (ESTRO) and Radiotherapy Oncology Group (RTOG) guidelines of volume definition and delineation guidelines. ResultsWith a median follow-up of 64 months (range: 6–102 months), 5-year locoregional recurrence-free and overall survival probabilities were 90 % (95 % confidence interval [95 %CI]: 88.1–92.4) and 90.9 % (95 %CI: 88.9–93), respectively. Among the 796 patients included in the study, 23 patients (2.9 %) presented locoregional recurrences of them only 13 (1.6%) were presented with local recurrence. The majority of them presented aggressive biological features with grade III tumours in 17 patients (74 %) with high mitotic index in 16 cases (70 %) and triple negative tumours in 12 (52 %). Lymphovascular invasion was observed in 11 cases (48 %). In 14 cases the locoregional recurrences were diagnosed at the same time as the metastatic disease whereas 4 patients presented distant metastases secondarily. Locoregional recurrences occurred in 11 cases “in field” although adequate doses and volumes were used and in 12 cases “outfield”, out of irradiated volume. Local recurrences occurred in 13 patients with 12 recurrences within the irradiated volumes. Regional recurrences occurred in 13 patients with 15 lymph nodes metastases identified. Four nodal recurrences occurred outside the ESTRO clinical target volume and within the RTOG clinical target volume and two occurred outside both RTOG and ESTRO clinical target volumes. ConclusionIn presented series, the local recurrence resulted mostly from of biologic radio resistance whereas regional recurrences were caused by geographical miss. A number of nodal recurrences could occur outside the target volumes defined by ESTRO and RTOG.

Use of 18F-FDG PET/CT Imaging for Radiotherapy Target Volume Delineation after Induction Chemotherapy and for Prognosis of Locally Advanced Squamous Cell Carcinoma of the Head and Neck.

Background and objectives: Induction chemotherapy (ICT) before definitive chemoradiation (CRT) gives high response rates in locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN). However, pre-ICT gross tumor volume (GTV) for radiotherapy (RT) planning is still recommended. As 18F-FDG PET/CT has an advantage of biological tumor information comparing to standard imaging methods, we aimed to evaluate the feasibility of 18F-FDG PET/CT-based post-ICT GTV delineation for RT planning in LA-SCCHN and to assess the prognostic value of PET parameters: maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG). Methods: 47 LA-SCCHN patients were treated with 3 cycles of ICT (docetaxel, cisplatin, and 5-fluorouracil) followed by CRT (70 Gy in 35 fractions with weekly cisplatin). Pre- and post-ICT PET/CT examinations were acquired. Planning CT was co-registered with post-ICT PET/CT and RT target volumes were contoured according to post-ICT PET. Post-ICT percentage decrease of SUVmax, MTV and TLG in primary tumor and metastatic regional lymphnodes (LN) was counted. Loco-regional failure patterns, 3-year progression free (PFS) and overall survival (OS) were evaluated. Results: 3-year PFS and OS rates for study population were 67% and 61% respectively. 31.9% of patients progressed loco-regionally. All progress was localized in high-to-intermediate dose (60–70 Gy) RT volumes and none in low dose (50 Gy) volumes. Decrease of SUVmax ≥ 74% (p = 0.04), MTV ≥ 68% (p = 0.03), TLG ≥ 76% (p = 0.03) in primary tumor, and LN TLG decrease ≥ 74% (p = 0.03) were associated with PFS. Decrease of primary tumor SUVmax ≥ 74% (p = 0.04), MTV ≥ 69% (p = 0.03), TLG ≥ 74% (p = 0.02) and LN TLG ≥ 73% (p = 0.02) were prognostic factors for OS. Conclusions: According to our results, 18F-FDG PET/CT-based post-ICT GTV delineation is feasible strategy without negative impacts on loco-regional control and survival. Percentage decrease of metabolic PET parameters SUVmax, MTV and TLG has a prognostic value in LA-SCCHN.

Patterns of Local-Regional Failure After Intensity Modulated Radiation Therapy or Passive Scattering Proton Therapy With Concurrent Chemotherapy for Non-Small Cell Lung Cancer

We compared differences in patterns of locoregional failure, and the influence of adaptive planning on those patterns, in patients who received passive scattering proton therapy (PSPT) versus intensity modulated photon therapy (IMRT) for non-small cell lung cancer. Treatment simulation computed tomography scans and dose distributions were registered with images depicting the recurrence. Local failure (LF) was defined as failure within the internal target volume (ITV); marginal failure (MF) as failure between the ITV and planning target volume (PTV) plus a 10-mm margin (PTV+10mm); and regional failure (RF) as outside the PTV+10mm. Weekly during-treatment 4-dimensional computed tomography simulation and verification plans were obtained for all patients. Adaptive plans were developed if the verification plan showed deviations in protocol-specified dose distribution, and failure locations were recorded for those patients as well. Of the 212 patients analyzed, most (152 [72%]) had no failure; of the 60 patients with failure, 27 (45%) had LF (within the ITV), 23 (38%) had MF (between the ITV and PTV+10mm), and 10 (17%) had RF (>10mm outside the PTV). MF rates were no different for IMRT patients (16 of 136 [12%]) or PSPT patients (7 of 76 [9%], log-rank P=.558). The only independent predictor of MF on Cox proportional hazards analysis was T3-4 status. Large tumors and use of PSPT independently predicted the need for adaptive planning. Although 5-year overall survival rates were poorer for patients with large tumors versus small tumors (P<.001), the rates were similar for patients with large tumors who received adaptive planning versus small tumors. No differences in LF, MF, or RF patterns were found for IMRT versus PSPT. Proton therapy more often required adaptive planning, and the techniques used for adaptive planning did not compromise tumor control. Response to chemoradiation by larger tumors predicted favorable survival.

Incidence and Patterns of Locoregional Failure After Stereotactic Body Radiation Therapy for Pancreatic Adenocarcinoma

PurposeStereotactic body radiation therapy (SBRT) is increasingly utilized in the neoadjuvant and definitive settings for pancreatic adenocarcinoma. The risk of local and regional recurrence after this treatment remains largely unknown. Because of the lack of elective nodal treatment and high fractional dose, we hypothesized that the incidence of regional out-of-field recurrence would predominate after SBRT. Methods and materialsElectronic medical records of all patients treated in our department with SBRT for pancreatic adenocarcinoma were retrospectively reviewed. Patients were separated into those who converted or did not convert to surgical resectability. Demographic, treatment, and outcome data were collected and analyzed. Recurrence was assessed based on the Response Evaluation Criteria In Solid Tumors version 1.1. Treatment plans were reviewed to determine the locations of failure with respect to treatment volume. Statistical comparisons were made using Mann-Whitney U testing for continuous variables and χ2 testing for dichotomous variables. ResultsData on 69 patients was available for analysis. After treatment, 18 patients (26.1%) suffered in-field recurrence and 11 patients (15.9%) recurred regionally out of field. The median time to in-field and out-of-field failures were similar at 120.5 and 108.0 days, respectively (P = .65). Of those who failed out-of-field, 4 of 11 patients (36.4%) were without in-field failure prior to death. In-field failure rates were less in patients who subsequently underwent surgical resection compared with those who did not (2 of 22 patients [9.1%] vs 16 of 47 patients [34.0%]; P = .028), but out-of-field recurrence was unaffected by subsequent surgical resection (3 of 22 patients [13.6%] vs 8 of 47 patients [17.0%]; P = .720). All out-of-field failures occurred in areas that received <2600 cGy. ConclusionsThe incidence of out-of-field failure remains acceptable after SBRT for pancreatic adenocarcinoma. Despite the high biological equivalent dose allowed by SBRT, in-field control remains problematic and continues to signal relative radiation resistance that is associated with bulky disease.

(P31) Patterns of Failure Following Curative Treatment for Oral Cavity Squamous Cell Carcinoma, in Patients Receiving Post-Operative Radiotherapy +/- Chemotherapy, an Institutional Experience

To analyze patterns of loco-regional failure and evaluate treatment outcomes of oral cavity cancer patients undergoing surgery and adjuvant radiotherapy +/- chemotherapy. Our institutional head and neck database was queried for patients with stage I-IVB oral cavity squamous cell carcinoma, treated primarily with surgery followed by radiotherapy +/- chemotherapy. These patients were treated between 1990-2016, with either 3D-conformal radiotherapy or intensity modulated radiotherapy (IMRT). We analyzed patient survival as well as local and regional patterns of failure. Out of 243 eligible patients, 229 had survival data recorded with median follow-up time of 50.1 months. The median survival for the entire cohort was 82.5 months, and median progression free survival was 9.3 months. The 2-year OS, LC, and LRC was 67.5%, 63.9% and 49.6%, respectively. The tumor subsites represented were oral tongue (36.2%), floor of mouth (23.9%), alveolus and hard palate (19.3%), buccal mucosa (5.8%), retromolar trigone (13.2%) and lip (1.6%). Of the patients with local control data available, 71 of 223 had experienced local or regional failure. The majority of failures (73.2%, 51 of 71) were in-field, followed by persistent disease (11 of 71), with 4 failures out-of-field and 4 with both in-field and out-of-field failures. Nearly three-quarters of local failures were in-field, and 15.5% of local failures consisted of persistent disease. The vast majority of local failures continues to be within the radiation treatment field for patients receiving post-operative radiotherapy.

EP-1304: Patterns of loco-regional failure in early breast cancer treated by WBRT in lateral position

EP-1304: Patterns of loco-regional failure in early breast cancer treated by WBRT in lateral position

219 (PB-014) - Patterns of loco-regional failure in women with early stage breast cancer treated by whole breast radiotherapy in lateral position: Large scale single center experience

219 (PB-014) - Patterns of loco-regional failure in women with early stage breast cancer treated by whole breast radiotherapy in lateral position: Large scale single center experience