Tumor Bed Research Articles

Improving 3D dose prediction for breast radiotherapy using novel glowing masks and gradient-weighted loss functions.

The quality of treatment plans for breast cancer can vary greatly. This variation could be reduced by using dose prediction to automate treatment planning. Our work investigates novel methods for training deep-learning models that are capable of producing high-quality dose predictions for breast cancer treatment planning. The goal of this work was to compare the performance impact of two novel techniques for deep learning dose prediction models for tangent field treatments for breast cancer. The first technique, a "glowing" mask algorithm, encodes the distance from a contour into each voxel in a mask. The second, a gradient-weighted mean squared error (MSE) loss function, emphasizes the error in high-dose gradient regions in the predicted image. Four 3D U-Net deep learning models were trained using the planning CT and contours of the heart, lung, and tumor bed as inputs. The dataset consisted of 305 treatment plans split into 213/46/46 training/validation/test sets using a 70/15/15% split. We compared the impact of novel "glowing" anatomical mask inputs and a novel gradient-weighted MSE loss function to their standard counterparts, binary anatomical masks, and MSE loss, using an ablation study methodology. To assess performance, we examined the mean error and mean absolute error (ME/MAE) in dose across all within-body voxels, the error in mean dose to heart, ipsilateral lung, and tumor bed, dice similarity coefficient (DSC) across isodose volumes defined by 0%-100% prescribed dose thresholds, and gamma analysis (3%/3mm). The combination of novel glowing masks and gradient weighted loss function yielded the best-performing model in this study. This model resulted in a mean ME of 0.40%, MAE of 2.70%, an error in mean dose to heart and lung of -0.10 and 0.01Gy, and an error in mean dose to the tumor bed of -0.01%. The median DSC at 50/95/100% isodose levels were 0.91/0.87/0.82. The mean 3D gamma pass rate (3%/3mm) was 93%. This study found the combination of novel anatomical mask inputs and loss function for dose prediction resulted in superior performance to their standard counterparts. These results have important implications for the field of radiotherapy dose prediction, as the methods used here can be easily incorporated into many other dose prediction models for other treatment sites. Additionally, this dose prediction model for breast radiotherapy has sufficient performance to be used in an automated planning pipeline for tangent field radiotherapy and has the major benefit of not requiring a PTV for accurate dose prediction.

Trends in the treatment of human papillomavirus-associated oropharyngeal carcinoma in Slovakia.

The optimal treatment of oropharyngeal cancer (OPC) associated with human papillomavirus (HPV) is currently a subject of clinical research. This questionnaire study investigated current trends in the treatment of HPV-associated (HPV+) OPC in Slovakia with the incorporation of deintensification of oncological treatment into routine clinical practice outside of clinical trials. The Slovak Cooperative Head and Neck Cancer Group (SCHNCG) developed a questionnaire aimed at identifying trends in the oncological treatment of HPV+ OPC intended for all radiation oncology (RO) facilities in Slovakia. Specialists in the field of RO responded to general questions about the character of their individual institutions as well as to 4 theoretical clinical scenarios (case reports) regarding the treatment of HPV+ OPC, focusing primarily on the applied dose of radiotherapy (RT), the extent of target volumes, and the type of concurrent chemotherapy (CHT). The questionnaire study involved 35 RO specialists from 14 institutions in Slovakia. Regarding primary chemoradiotherapy (CRT) in T1N1M0 HPV+ OPC, 16 respondents (45.7%) would consider de-escalation of the RT dose to <70 Gy. In the case of postoperative RT in pT1pN1M0 HPV+ OPC with negative resection margins (R0) and absent extracapsular extension (ECE), 4 physicians (11.4%) would consider de-escalation of the RT dose to <60 Gy in the tumor bed area, while the majority of the treating specialists (n=19, 54.3%) would omit concurrent CHT. In the case of primary RT in elderly patient with T2N1M0 HPV+ OPC, the same number of physicians (n=16, 45.7%) would consider de-escalation of the RT dose to <70 Gy, and 14 respondents (40.0%) would completely omit CHT. In a high-risk patient with T2N3M0 HPV+ OPC with a complete response after 3 cycles of induction chemotherapy (iCHT), none of the respondents would indicate a reduction in the RT dose to the area of the original tumor and lymphadenopathy to <60 Gy. The doses and extent of irradiated volumes in the treatment of HPV+ OPC in Slovakia vary among different institutions. The tendency to de-escalate RT doses and reduce doses of concurrent systemic therapy in Slovakia is high and there was also an observed trend to reduce the extent of radiation treatment fields.

Current trends in marking the tumor bed for radiation therapy after breast-conserving surgery for breast cancer

Current trends in marking the tumor bed for radiation therapy after breast-conserving surgery for breast cancer

Uptake of ultra-hypofractionated radiation therapy following breast-conserving surgery among patients with early-stage breast cancer: a multi-institutional questionnaire survey.

In patients with early-stage breast cancer following breast surgery, ultra-hypofractionated (UHF) breast/chest wall radiation therapy (RT) has been shown to be non-inferior to a moderate-hypofractionated (MHF) regimen, with a minimal risk of breast induration, in the FAST-Forward trial, and UHF is now becoming the standard regimen in Europe. Herein, we aimed to investigate Japanese patients' attitudes toward the UHF regimen. A questionnaire-based survey was conducted at 13 RT centers in nine prefectures across Japan. All patients underwent breast-conserving surgery, followed by either conventional fractionation (2Gy/fr) or MHF (2.66Gy/fr) whole-breast irradiation (WBI) with or without a tumor bed boost. The questionnaire consisted of 13 questions mainly addressing quality-of-life during RT. Key questions included an 11-point scale (0-10) for rating the patients' enthusiasm for the UHF regimen and prioritization of the following treatment-related effects: treatment efficacy, acute/late adverse effects, physical/emotional/financial burden, and breast cosmesis. The patient and treatment characteristics were assessed by a physician. In total, 247 questionnaires were administered between November 2022 and June 2023. The age distribution was as follows: < 50:50s:60s: ≥ 70 = 59 (24%):76 (30%):63 (26%):49 (20%). Sixty-nine percent of patients rated their enthusiasm for the UHF regimen at ≥ 6 out of 10 points (45% rated 10/10). Treatment efficacy was the highest priority for most patients (89%), whereas breast cosmesis the lowest priority (53%). Patients' enthusiasm for UHF-WBI was observed across the cohort. These results could motivate researchers and clinicians to introduce UHF regimens in clinical practice.

Long-term clinical outcomes of male breast cancer patients treated with curative intent by trimodality therapy at an academic university hospital in India.

Male breast cancer is rare and accounts for less than 1% of all breast cancer cases worldwide. This retrospective cohort study included all patients of invasive male breast cancer treated with curative intent by a trimodality approach via a multidisciplinary team at an academic university hospital in India between 2009 and 2023. Records were identified from a prospectively maintained database. Clinicopathological parameters, treatment details and survival were recorded and analysed. Thirty-four patients were included. The median (IQR) age was 55(44-63) years. Most patients were overall stage III (74%) and node positive (79%) with Scarff-Bloom-Richardson grade II (50%). Twenty-five patients (73%) were oestrogen receptor (ER) positive. Lymphovascular space invasion (LVSI) and perineural invasion (PNI) were present in 62% and 21% of patients, respectively. The most common chemotherapy timing was adjuvant (53%) followed by neoadjuvant (41%), and the most commonly used regimen consisted of a combination of doxorubicin-cyclophosphamide followed by a taxane (53%). Most (85%) patients underwent a mastectomy, five patients underwent breast conservation. All patients received radiotherapy to a dose of 42.6 Gy in 16 fractions, followed by a tumour bed boost for those undergoing breast conservation. At a median follow-up of 70 months (range 10-159 months), the five and ten-year overall survival was 91% and 58%, and the five-year disease-free survival (DFS) was 67%. The median DFS was 72 months. On univariate analysis, the tumour sub-type (Luminal versus TNBC) significantly predicted DFS (P = 0.03 log-rank). Breast cancer in males has a high incidence of node positivity, ER positivity and LVSI. Even with advanced stages at presentation, trimodality therapy in a multidisciplinary setting offers good long-term outcomes.

Non-Invasive 3D Breast Tumor Localization: A Viable Alternative to Invasive Tumor Marking.

Background: We present a detailed description and the preliminary results of our original technique for non-invasive three-dimensional tumor localization in the breast, which was created as an alternative to standard invasive tumor marking before neoadjuvant systemic therapy (NAST), aiming to enable adequate surgery after complete tumor regression. Methods: A detailed description of the technique is provided in the main text. The technique's feasibility and precision were assessed in a single-arm, prospective study based on the histological parameters of the adequacy and rationality of the excision of completely regressed tumor beds. Results: Out of 94 recruited patients, 15 (16%) were deemed unsuitable, mainly due to the tumors' inadequate ultrasound visibility. Among the 79 processed patients, 31 (39%) had complete clinical regression after NAST and were operated on using our technique. The histological parameters of surgical precision (signs of tumor regression: 24/31; microscopic cancer residues: 7/31) were verified in all excised specimens (100% precision). There were no positive margins in seven cases with microscopic residues, indicating our technique's capacity to enable oncologically safe post-NAST surgery. Conclusions: The proposed technique is feasible and satisfactorily accurate in determining the location of regressed tumors, thus representing an alternative to invasive tumor marking, especially in surgical centers lacking trained staff and equipment for invasive marking. The technique's limitations are mainly related to the inadequate ultrasound visibility of the tumor.

Evaluation of pathological response to neoadjuvant chemotherapy in locally advanced cervical cancer

Neoadjuvant chemotherapy (NACT) is a viable therapeutic option for women diagnosed locally advanced cervical cancer (LACC). However, the factors influencing pathological response are still controversial. We collected pair specimens of 185 LACC patients before and after receiving NACT and conducted histological evaluation. 8 fresh tissues pre-treatment were selected from the entire cohort to conducted immune gene expression profiling. A novel pathological grading system was established by comprehensively assessing the percentages of viable tumor, inflammatory stroma, fibrotic stroma, and necrosis in the tumor bed. Then, 185 patients were categorized into either the good pathological response (GPR) group or the poor pathological response (PPR) group post-NACT, with 134 patients (72.4%, 134/185) achieving GPR. Increasing tumor-infiltrating lymphocytes (TILs) and tumor-infiltrating lymphocytes volume (TILV) pre-treatment were correlated with GPR, with TILV emerging as an independent predictive factor for GPR. Additionally, CIBERSORT analysis revealed noteworthy differences in the expression of immune makers between cPR and non-cPR group. Furthermore, a significantly heightened density of CD8 + T cells and a reduced density of FOXP3 + T cells were observed in GPR than PPR. Importantly, patients exhibiting GPR or inflammatory type demonstrated improved overall survival and disease-free survival. Notably, stromal type was an independent prognostic factor in multivariate analysis. Our study indicates the elevated TILV in pre-treatment specimens may predict a favorable response to NACT, while identifying stromal type in post-treatment specimens as an independent prognostic factor. Moreover, we proposed this pathological grading system in NACT patients, which may offer a more comprehensive understanding of treatment response and prognosis.

Locoregional Recurrence in Adenoid Cystic Carcinoma of the Breast: A Retrospective, Multicenter Study (KROG 22-14).

This study aims to evaluate the treatment approaches and locoregional patterns for Adenoid cystic carcinoma (ACC) in the breast, which is an uncommon malignant tumor with limited clinical data. A total of 93 patients diagnosed with primary ACC in the breast between 1992 and 2022 were collected from multi-institutions. All patients underwent surgical resection, including breast-conserving surgery (BCS) or total mastectomy (TM). The recurrence patterns and locoregional recurrence-free survival (LRFS) were assessed. Seventy-five patients (80.7%) underwent BCS, and 71 of them (94.7%) received post-operative radiation therapy (PORT). Eighteen patients (19.3%) underwent TM, with 5 of them (27.8%) also receiving PORT. With a median follow-up of 50 months, the LRFS rate was 84.2% at 5 years. Local recurrence (LR) was observed in 5 patients (5.4%) and 4 cases (80%) of the LR occurred in the tumor bed. Three of LR (3/75, 4.0%) had a history of BCS and PORT, meanwhile, two of LR (2/18, 11.1%) had a history of mastectomy. Regional recurrence occurred in 2 patients (2.2%), and both cases had a history of PORT with (n=1) and without (n=1) irradiation of the regional lymph nodes. Partial breast irradiation (p=0.35), BCS (p=0.96) and PORT in BCS group (p=0.33) had no significant association with LRFS. BCS followed by PORT was the predominant treatment approach for ACC of the breast and local recurrence mostly occurred in the tumor bed. The findings of this study suggest that partial breast irradiation might be considered for PORT in primary breast ACC.

Surgical cavity dilatation after resection of IDH-mutated astrocytoma of the mesial temporal lobe: illustrative cases.

Space-occupying tumor bed cysts may exceptionally happen after the resection of diffuse low-grade glioma. Their mechanism and management remain debated. The authors report two cases of tumor bed cysts occurring after the resection of a left temporal diffuse low-grade glioma with two different evolutions. The first patient showed a spontaneous decrease in the cyst volume and did not report any symptoms. In contrast, the second patient showed a progressive increase in the cyst volume and reported headaches and difficulties in finding words. Endoscopic cyst fenestration was performed and led to symptom relief and normalization of the surgical cavity. A tumor bed cyst is a rare complication of temporal low-grade glioma resection. Its formation is due to entrapment of the choroid plexus in the temporal horn widely opened into the surgical cavity. Endoscopic cyst fenestration should be offered only in symptomatic cases. https://thejns.org/doi/10.3171/CASE23674.

"Target-and-release" nanoparticles for effective immunotherapy of metastatic ovarian cancer.

Immunotherapies such as checkpoint inhibitors (CPI) are effective in treating several advanced cancers, but these treatments have had limited success in metastatic ovarian cancer (OC). Here, we engineered liposomal nanoparticles (NPs) carrying a layer-by-layer (LbL) polymer coating that promotes their binding to the surface of OC cells. Covalent anchoring of the potent immunostimulatory cytokine interleukin-12 (IL-12) to phospholipid headgroups of the liposome core enabled the LbL particles to concentrate IL-12 in disseminated OC tumors following intraperitoneal administration. Shedding of the LbL coating and serum protein-mediated extraction of IL-12-conjugated lipids from the liposomal core over time enabled IL-12 to disseminate in the tumor bed following rapid NP localization in tumor nodules. Optimized IL-12 LbL-NPs promoted robust T cell accumulation in ascites and tumors in mouse models, extending survival compared to free IL-12 and remarkedly sensitizing tumors to CPI, leading to curative treatments and immune memory.

Comparative Evaluation of USG-Guided Single Tissue Marker Versus Multiple Tissue Marker Placements in Breast Malignancy Patients Undergoing Neoadjuvant Chemotherapy for Tumor Localization.

Background Breast cancer remains one of the most common malignancies affecting women globally, contributing significantly to the disease burden. The advent of neoadjuvant chemotherapy (NAC) has revolutionized the treatment for locally advanced breast cancer, allowing tumors to be downstaged and making breast-conserving surgery (BCS) feasible. Accurate localization of the tumor bed post-NAC is crucial for successful surgical removal of residual disease. While traditional single tissue marker placement has been effective, recent advances suggest multiple markers might provide superior localization by comprehensively delineating the entire tumor area. This study aims to compare the effectiveness of single versus multiple tissue marker placements in breast malignancy patients undergoing NAC. Materials and methods A prospective study was conducted in the Department of Radio-diagnosis at Saveetha Medical College over 18 months, including 10 patients diagnosed with breast carcinoma, selected through convenience sampling. Inclusion criteria involved patients diagnosed with breast cancer via mammography, sonography, and histological confirmation, referred for clip placement before NAC. Exclusion criteria were patients unwilling to participate. The procedure involved placing one to two surgical clips within the tumor using a 14/16-gauge coaxial guiding needle under USGguidance, with additional clips for larger or multiple tumors. Data collection included pre-procedural USG, post-procedural mammography (MG1), pre-operative mammography (MG2)/USG, and gross specimen histopathological examination/specimen mammography. Statistical analysis Demographic data, clipping distribution, receptor status, localization methods, surgical outcomes, operation diagnoses, and correlation analysis were statistically analyzed. Mean age, standard deviation, and p-values were calculated to determine the significance of differences between single and multiple clip groups. Results The study included 10 patients with a mean age of 52.5 years. Of these, five (50%)had a single clip, and two (20%)had four clips. The average time from clipping to the second mammogram (MG2) was 106.3 days, and from clipping to operation was 111.0 days, with longer follow-up times for multiple clip patients. Six (60%) of the patients were estrogen receptor (ER) positive, and six (60%) were human epidermal growth factor receptor 2 (HER2) negative. Localization methods were similar between single and multiple clip groups. However, multiple clip patients tended to undergo more extensive surgeries like modified radical mastectomy (MRM). Imaging responses showed no preoperative ultrasound lesions in single clip patients, while multiple clip patients had higher inconsistent diagnoses (10 (100%)) suggesting that multiple clips provide better tumor localization but are linked to increased complexity and longer follow-up times. Conclusion Patients with multiple clips experienced significantly longer follow-up times, reflecting more complex clinical scenarios. Despite no significant differences in receptor status distributions, multiple clip patients required more extensive surgeries, emphasizing the need for tailored surgical planning. The study underscores the importance of considering the number of clips in clinical decision-making. Future research should focus on larger, prospective studies to validate these findings and explore underlying mechanisms.

Hypofractionated versus Conventional Postmastectomy Irradiation for Breast Cancer: Comparison of Acute Skin Toxicity.

Breast cancer is the leading cause of cancer mortality among women. Radiotherapy can reduce recurrence and prolong survival of patients accepting breast-conserving surgery (BCS). This study aims to compare acute skin reactions in patients receiving hypofractionated versus conventional radiotherapy at a single institution and to summarize the relevant influencing factors. This study analyzed 152 patients who underwent either hypofractionated or conventional whole-breast irradiation (WBI) after BCS. Acute skin toxicity was assessed according to the Radiation Therapy Oncology Group (RTOG) criteria. Predictive factors for acute skin toxicity were identified using multivariate analysis and visualized using a forest spot. Grade 0 reactions occurred in 75.34% vs 70.89%, grade 1 in 16.44% vs 15.19%, grade 2 in 8.22% vs 12.66%, and grade 3 in 0% vs 1.27% of patients receiving hypofractionated and conventional WBI, respectively. There was no statistically significant difference in acute skin reaction in patients treated with hypofractionated radiation compared with conventional radiation (P = 0.62). Multivariate analysis revealed that metastatic lymph nodes (P = 0.021), whole-breast planning target volume (PTV-WB) (P < 0.001), and tumor bed planning target volume (PTV-TB) (P = 0.002) were significantly correlated with higher rates of acute skin toxicity. Hypofractionated WBI demonstrated similar acute skin adverse reactions compared to conventional WBI. These findings indicate that hypofractionated radiotherapy offers comparable tolerance, equivalent curative effect, convenience, andeconomic benefits, supporting its clinicalpromotion.

Adjuvant and Neoadjuvant Therapy for Breast Cancer: A Systematic Review.

Breast cancer (BC) is the most frequent type of cancer among women. The neoadjuvant therapy was administered before surgery, and the adjuvant therapy was administered post-surgery. The goal of this systematic review is to study the effects of adjuvant and neoadjuvant BC therapy on patient outcomes and mortality. In July 2023, systematic searches were conducted through the Cochrane Library, Web of Sciences, Google Scholar, EMBASE, and PubMed databases. The search method focused on studies that included all patients with BC stages 1, 2, and 3 and excluded studies that included patients with metastatic and recurrent BC. The risk of bias in the included studies was evaluated using the Cochrane risk of bias technique. Throughout our search, 27 relevant studies with 161,552 patients were discovered. Anti-human epidermal growth factor 2 therapy (trastuzumab, pertuzumab), chemotherapy (anthracycline), endocrine therapy (tamoxifen, aromatase inhibitor), and bisphosphonates were recommended treatments for BC patients. Choices for radiotherapy included whole breast, partial breast, tumor bed boost, regional nodes, and chest wall choices after breast-conserving surgery. We discover that while the majority of treatments reduced the mortality or recurrence rates of BC, anthracycline, chemotherapy, and radiation led to an overall rise in non-BC deaths. The systemic assessment discovered several variables that impact a patient's quality of life. Based on these advantages and disadvantages, various treatment options for patients and recommendations for groups of women are made.

Watch and Wait in Rectal Cancer Patients with Residual Mucin on MRI following Neoadjuvant Therapy.

Neoadjuvant therapy (NAT) leads to a clinical complete response (cCR) in a significant proportion of patients with locally advanced rectal cancer (LARC), allowing for possible nonoperative management. The presence of mucin on MRI after NAT leads to uncertainty about residual disease and appropriateness of a watch-and-wait (WW) strategy in patients with no evidence of disease on proctoscopy (endoscopic cCR). MRI reports for LARC patients seen between July 2016 and January 2020 at Memorial Sloan Kettering Cancer Center were queried for presence of mucin in the tumor bed on MRI following NAT. Clinicodemographic, pathologic, and outcome data were compiled and analyzed. Of 71 patients with mucin on post-treatment MRI, 20 had a cCR and 51 had abnormalities on endoscopy and/or physical exam. One patient with a cCR opted out of WW; thus, 19 patients (27%) entered WW and 52 patients (73%) were planned for surgery (Non-WW). Of the 19 WW patients, 15 (79%) have had no local regrowth with median follow-up of 50 months (range, 29-76 months), while 4 (21%) experienced regrowth between 9 and 29 months after neoadjuvant therapy. Of the 52 patients who were planned to have surgery (Non-WW), 49 underwent resection while 3 developed metastatic disease that precluded curative-intent surgery. Five (10%) of the 49 patients who underwent surgery, including the one with an endoscopic cCR, had a pathologic complete response. The presence of mucin after NAT for LARC does not preclude WW management in otherwise appropriate candidates who achieve an endoscopic cCR.

Optimizing Morbidity in Unplanned Soft Tissue Sarcoma Excisions: Should We Skip the Reconstructive Ladder?

Soft tissue sarcomas (STSs) are rare and diverse primary malignant tumors that comprise approximately 1% of all malignancies. Misdiagnoses and unplanned excisions of STSs are common due to the tumor's rarity, leading to secondary tumor bed excisions (TBEs). Reconstructive outcomes for TBEs remain poorly understood, prompting this study to address the knowledge gap and inform preoperative discussions. This was a retrospective cohort study of patients who underwent STS excisions at a quaternary cancer center. Patients were categorized into mass excision (ME) and TBE groups. Reconstructive approaches were divided into simple (primary closure, complex repair, skin grafts, local flaps) and advanced (pedicled or free flaps). The groups were compared for postoperative outcomes, including complications, recurrence, and death. When simple reconstructive techniques were used, TBEs exhibited higher rates of overall and major complications, whereas MEs had higher rates of overall and minor complications. Intergroup analysis revealed that with simple reconstruction, rates of overall and major complications were higher in TBEs than in MEs, and rates of minor complications were higher in MEs than in TBEs. Regression analyses revealed that simple reconstruction of TBEs had 90% and 180% higher odds of major complications and reoperation compared to simple reconstruction of MEs (P < 0.05). TBEs, despite their smaller size, exhibited a heightened susceptibility to overall and major complications, challenging the notion that simpler techniques suffice in these cases. Our findings encourage the consideration of advanced reconstructive techniques for TBEs that may seem amenable to simple reconstructive techniques.

Automatic Detection of Post-Operative Clips in Mammography Using a U-Net Convolutional Neural Network.

After breast conserving surgery (BCS), surgical clips indicate the tumor bed and, thereby, the most probable area for tumor relapse. The aim of this study was to investigate whether a U-Net-based deep convolutional neural network (dCNN) may be used to detect surgical clips in follow-up mammograms after BCS. 884 mammograms and 517 tomosynthetic images depicting surgical clips and calcifications were manually segmented and classified. A U-Net-based segmentation network was trained with 922 images and validated with 394 images. An external test dataset consisting of 39 images was annotated by two radiologists with up to 7 years of experience in breast imaging. The network's performance was compared to that of human readers using accuracy and interrater agreement (Cohen's Kappa). The overall classification accuracy on the validation set after 45 epochs ranged between 88.2% and 92.6%, indicating that the model's performance is comparable to the decisions of a human reader. In 17.4% of cases, calcifications have been misclassified as post-operative clips. The interrater reliability of the model compared to the radiologists showed substantial agreement (κreader1 = 0.72, κreader2 = 0.78) while the readers compared to each other revealed a Cohen's Kappa of 0.84, thus showing near-perfect agreement. With this study, we show that surgery clips can adequately be identified by an AI technique. A potential application of the proposed technique is patient triage as well as the automatic exclusion of post-operative cases from PGMI (Perfect, Good, Moderate, Inadequate) evaluation, thus improving the quality management workflow.

LMIC-03. BRAINSTEM RADIATION NECROSIS IN A PATIENT WITH RECURRENT MEDULLOBLASTOMA. SUCCESFULL TREATMENT OF A HIGHLY FEARED COMPLICATION

Abstract BACKGROUND Medulloblastoma is the most common malignant brain tumor in pediatric population. Standard treatment combines surgery, risk-adapted craniospinal irradiation and chemotherapy. Given the well-known cognitive sequelae in young children associated to radiation, strategies in infants try to avoid upfront radiation. A significant number of patients treated during infancy will ultimately relapse. Re-irradition in relapse setting has proven to be effective in disease control (survival depending on several factors) although there is a concern in exceeding radiation tolerance and risk of toxicity. METHODS Herein, we describe the case of male patient that presented at 1 year of age with a non-metastatic anaplastic medulloblastoma that was completely resected. He received 3 cycles of adjuvant chemotherapy (as per Head Start II), local relapse was detected in tumor bed during evaluation and was completely resected, afterwards he received myeloablative chemotherapy with stem cell rescue and posterior fossa radiation therapy (54 Gy). At 8 months off therapy patient developed spinal relapse in imaging with negative cytology, then treated with spinal irradiation 36Gy without adjuvant chemotherapy. He remained disease free during 12 months, then tumor recur at the right cerebellopontine angle, surgery was complete and there was no evidence of distant disease. Patient received adjuvant local radiation with 30.6Gy followed by chemotherapy (bi weekly bevacizumab + irinotecan). Cumulative maximal dose to brainstem was 84Gy. 2 months after radiation patient presented with extreme sleepiness and imaging findings compatible with brainstem radiation necrosis, symptoms resolved promptly after scheduled bevacizumab. Patient is currently 6-year-old and remains free of disease after 3 years off therapy. CONCLUSION Medulloblastoma treatment in infants is challenging because survival is not the only goal. Future clinical trials will help to better tailored treatment based on molecular biology. Re-irradiation in medulloblastoma has been described as well tolerated but clinician should be aware of its complications and management.

ATRT-06. PEDIATRIC INI1-NEGATIVE ATYPICAL TERATOID RHABDOID TUMORS TREATED WITH TAZEMETOSTAT AS MAINTENANCE THERAPY IN THE RELAPSE SETTING: AN ITALIAN SINGLE-CENTRE EXPERIENCE

Abstract BACKGROUND Rhabdoid tumors are aggressive malignancies, primarily affecting children ≤3 years. Common sites of primary localization are kidney, central nervous system (atypical teratoid rhabdoid tumor -AT/RT-) or soft tissues. Although high-dose chemotherapy (HD-CT) with radiotherapy (RT) has significantly increased EFS and OS rates, more than 50% of patients diagnosed with AT/RT still die of tumor progression. METHODS From February 2021 to January 2024 three patients with AT/RT were treated with tazemetostat after first-line treatment (complete resection, CT, RT). RESULTS At diagnosis, patient 1 presented with a lesion in the lamina quadrigemina and a renal mass; patient 2 and 3 with a lesion in the posterior cranial fossa. Median age at diagnosis was 8 months (3-34 months). Patient 1 died due to the progression of the disease (OS 24 months); patient 2 ended treatment with tazemetostat on December 2023; for patient 3 the treatment is still ongoing. Patient 1 started tazemetostat at the end of first-line treatment, as maintenance therapy. Before starting treatment with tazemetostat, patient 2 performed a re-irradiation on the tumor bed; patient 3 performed surgery and then RT on a new-onset spinal lesion. Median time of treatment with tazemetostat was 9 months (6-12 months). Patient 1 showed an EFS of 9 months. EFS of patients 2 and 3 has exceeded this timepoint. For patient 2 the treatment is ongoing (in total 6 months of treatment), with a complete response of the disease (CR); patient 3 ended treatment after 12 months, with a CR. Tazemetostat was overall well tolerated. CONCLUSIONS Despite the small number of patients, we feel able to state that the use of tazemetostat as a single agent in the relapse setting could represent a therapeutic promise as maintenance therapy. Future studies with a larger number of patients are needed to confirm this hypothesis.

TRLS-11. PNOC005: ONCOLYTIC MEASLES VIRUS FOR THE TREATMENT OF CHILDREN AND YOUNG ADULTS WITH RECURRENT MEDULLOBLASTOMA OR ATYPICAL TERATOID RHABDOID TUMOR

Abstract BACKGROUND PNOC005 is a phase 1 clinical trial investigating the safety and tolerability of intratumoral or intrathecal administration of oncolytic measles virus (MV-NIS) in children and young adults with recurrent medulloblastoma (MB) or atypical teratoid/rhabdoid tumor (ATRT). METHODS Patients with recurrence of MB or ATRT were stratified into Stratum A (local recurrence) or B (disseminated recurrence). Stratum A patients received MV-NIS directly into the tumor bed at time of surgical resection. Stratum B patients received a single dose of MV-NIS via lumbar puncture. After safety was demonstrated in Stratum A and B, Stratum C was added with repeat dosing on Day 0 and 7 for patients with recurrent disseminated MB. Specimens for viral shedding were collected. Blood was collected on days 0, 4, 7, 14, and 28. RNA-sequencing deconvolution and time-series analysis were performed to estimate the composition and phenotypes of peripheral blood mononuclear cells (PBMCs). RESULTS Thirty-four patients (median age 8.5, range 2-31) enrolled between February 2017 and April 2021, with 23 evaluable patients with MB and 4 with ATRT. One patient experienced a dose-limiting toxicity (grade 3 alanine aminotransferase increase). There were four MV-NIS-related adverse events grade 3 or greater across all strata. Viral shedding was detected in 5 patients, all of which cleared by end-of-treatment. We found a similar gene-expression program in PMBCs that correlated across patients (n=18), which was upregulated at days 4-7 post treatment and consistent with an antiviral response. Concomitant changes in B, T, and natural-killer cell composition and activation were consistent with this interpretation. CONCLUSION This is the first trial investigating intratumoral as well as repeated intrathecal delivery of MV-NIS in children with MB and ATRT. We show that therapy is safe and well-tolerated with minimal adverse effects. Immune markers and biologic correlates preliminarily indicate anti-viral effects in tumors.

HGG-45. HIGH GRADE GLIOMA PRESENTING AS A SYNCHRONOUS CANCER IN A PATIENT WITH DIFFUSE LARGE B CELL LYMPHOMA: A UNIQUE TREATMENT DILEMMA

Abstract BACKGROUND Patients with synchronous tumors pose significant treatment dilemmas. We present a pediatric patient found to have concomitant Diffuse Large B-cell Lymphoma (DLBCL) and a High Grade Glioma (HGG). His unique presentation and family history uncovered a familial diagnosis of Lynch Syndrome. CASE A 7-year-old male presented with acute appendiceal rupture. Surgical resection identified an appendiceal mass consistent with localized DLBCL. While undergoing staging evaluations, the patient complained of new onset blurry vision with normal neurologic and ophthalmologic exams. Subsequent imaging was concerning for a high-grade lesion. Biopsy confirmed HGG and he underwent gross total resection. Family history included a brother with relapsed leukemia status post bone marrow transplant and multiple first cousins with lymphoma and gastrointestinal cancers. RESULTS While awaiting genetics and mutational analysis, we initiated treatment. The HGG was treated with focal radiation to the tumor bed starting 2 weeks after resection. Lymphoma therapy was initiated concurrently per the REBOOT regimen with the goal of decreasing doxorubicin dosing during radiation. Lumbar punctures and intrathecal chemotherapy were deferred until completion of radiation. Biopsy of residual abdominal masses following consolidation 1 showed &amp;lt;5% viable cells and therapy was intensified to ANHL1331, Group C1. Evaluation of both lesions identified hypermutation (mutational burden &amp;gt; 150mutations/Mb). Two unique germline mutations of PMS2 were also identified, consistent with Lynch syndrome. After completion of above therapy, the patient received maintenance therapy with nivolumab checkpoint inhibition. The patient developed severe neutropenia leading to cessation of nivolumab and quick progression of his HGG. CONCLUSION Synchronous tumors pose significant treatment dilemmas given the need to treat multiple lesions while balancing side effects. While checkpoint inhibitors may provide a way to address multiple lesions, our patient had unacceptable side effects limiting the utility of this therapy.