Definitive External Beam Radiation Therapy Research Articles

Radiation-Induced Cranial Nerve Palsy: A Cross-Sectional Study of Nasopharyngeal Cancer Patients After Definitive Radiotherapy

To address the characteristics and the causative factors of radiation-induced cranial nerve palsy (CNP) in nasopharyngeal carcinoma (NPC) patients with an extensive period of followed-up. A total of 317 consecutive and nonselected patients treated with definitive external-beam radiotherapy between November 1962 and February 1995 participated in this study. The median doses to the nasopharynx and upper neck were 71 Gy (range, 55-86 Gy) and 61 Gy (range, 34-72 Gy), respectively. Conventional fractionation was used in 287 patients (90.5%). Forty-five patients (14.2%) received chemotherapy. The median follow-up was 11.4 years (range, 5.1-38.0 years). Ninety-eight patients (30.9%) developed CNP, with a median latent period of 7.6 years (range, 0.3-34 years). Patients had a higher rate of CNP (81 cases, 25.5%) in lower-group cranial nerves compared with upper group (44 cases, 13.9%) (χ(2) = 34.444, p < 0.001). Fifty-nine cases experienced CNP in more than one cranial nerve. Twenty-two of 27 cases (68.8%) of intragroup CNP and 11 of 32 cases (40.7%) of intergroup CNP occurred synchronously (χ(2) = 4.661, p = 0.031). The cumulative incidences of CNP were 10.4%, 22.4%, 35.5%, and 44.5% at 5, 10, 15, and 20 years, respectively. Multivariate analyses revealed that CNP at diagnosis, chemotherapy, total radiation dose to the nasopharynx, and upper neck fibrosis were independent risk factors for developing radiation-induced CNP. Radiation-induced fibrosis may play an important role in radiation-induced CNP. The incidence of CNP after definitive radiotherapy for NPC remains high after long-term follow-up and is dose and fractionation dependent.

Chemo-radiation with or without mandatory split in anal carcinoma: experiences of two institutions and review of the literature

BackgroundThe split-course schedule of chemo-radiation for anal cancer is controversial.MethodsEighty-four patients with invasive anal cancer treated with definitive external beam radiotherapy (RT) with a mandatory split of 12 days (52 patients, Montreal, Canada) or without an intended split (32 patients, Zurich, Switzerland) were reviewed. Total RT doses were 52 Gy (Montreal) or 59.4 Gy (Zurich) given concurrently with 5-FU/MMC.ResultsAfter a mean follow-up of 40 ± 27 months, overall survival and local tumor control at 5 years were 57% and 78% (Zurich) compared to 67% and 82% (Montreal), respectively. Split duration of patients with or without local relapse was 15 ± 7 d vs. 14 ± 7 d (Montreal, NS) and 11 ± 11 d vs. 5 ± 7 d (Zurich; P < 0.001). Patients from Zurich with prolonged treatment interruption (≥ 7 d) had impaired cancer-specific survival compared with patients with only minor interruption (<7 d) (P = 0.06). Bowel toxicity was associated with prolonged RT (P = 0.03) duration as well as increased relapse probability (P = 0.05). Skin toxicity correlated with institution and was found in 79% (Montreal) and 28% (Zurich) (P < 0.0001).ConclusionsThe study design did not allow demonstrating a clear difference in efficacy between the treatment regimens with or without short mandatory split. Cause-specific outcome appears to be impaired by unplanned prolonged interruption.

Long-term Biochemical Control and Survival in High-risk Prostate Cancer Patients Treated with Seed Implant-based Therapy

Long-term Biochemical Control and Survival in High-risk Prostate Cancer Patients Treated with Seed Implant-based Therapy

Cost Analysis of Prostatectomy followed by Postoperative Radiotherapy vs. Definitive Radiotherapy and Androgen Deprivation

The treatment of intermediate-risk prostate cancer can include prostatectomy, radiotherapy (RT), and androgen deprivation therapy (ADT). Two current standards of care as established by large Phase III trials are radical prostatectomy followed by postoperative RT (RRP+PORT) and definitive external beam RT (EBRT) with neoadjuvant and concurrent ADT (EBRT+NADT). There have not been any Phase III trials comparing these two options. A third viable option currently being studied is EBRT with brachytherapy boost (EBRT+BB) and NADT.

Electromagnetic Tracking of Intrafraction Prostate Displacement among Patients Externally Immobilized in the Prone Position

Electromagnetic Tracking of Intrafraction Prostate Displacement among Patients Externally Immobilized in the Prone Position

PSA Kinetics following High Dose Intensity Modulated External Beam Radiation Therapy with and without Image Guidance

It has previously been reported that PSA kinetics in the first year following definitive external beam radiation therapy are predictive of biochemical progression-free and overall survival in patients treated with radiation therapy alone. In this study, we evaluated PSA kinetics in the first two years following high-dose intensity modulated external beam radiation therapy (IMRT) with and without image guidance.

7001 Oncologist case load volume and disease outcomes after definitive external beam radiotherapy for localized prostate cancer

7001 Oncologist case load volume and disease outcomes after definitive external beam radiotherapy for localized prostate cancer

Salvage permanent perineal radioactive‐seed implantation for treating recurrence of localized prostate adenocarcinoma after external beam radiotherapy

To assess our experience with salvage permanent perineal radioactive-seed implantation (SPPI) as a possible therapeutic option for recurrent prostate adenocarcinoma, as salvage therapies for recurrences after definitive external beam radiotherapy (EBRT) for localized adenocarcinoma of the prostate are associated with significant morbidity and biochemical failure. We retrospectively analysed on patients who had SPPI for localized recurrent prostate adenocarcinoma from 1996 to 2007 after primary treatment with EBRT. Excluded were patients who had other primary treatment or had no follow-up. Primary outcomes were time to biochemical relapse-free survival, using the Phoenix definition of a prostate-specific antigen (PSA) nadir +2 ng/mL, and cancer-specific survival. Secondary outcomes were the International Prostate Symptom Score (IPSS), the International Index of Erectile Function-5 score (IIEF-5), and complications based on Common Terminology Criteria for Adverse Events (version 3). In all, 37 patients had SPPI during this period; after applying inclusion and exclusion criteria, 24 remained for analysis. At the time of salvage therapy, the median time to the diagnosis of local recurrence was 49 months, the median PSA level was 3.36 ng/mL, the median PSA doubling time was 20 months, and all patients were clinically re-staged at <or=T2 with negative transrectal ultrasonography and/or magnetic resonance spectroscopy. The original Gleason score was <or=6 in nine patients, 7 in eight and >or=8 in three (not recorded in two). The median follow-up after SPPI was 30 months; the cancer-free survival was 96% (one death) and biochemical relapse-free survival was 88% (three patients). The PSA level was higher than the levels before SPPI at 3 months in all three failures, but lower in all 21 patients considered relapse-free. Complications included one urethral stricture, one grade 3 rectal haemorrhage and five grade 2 gross haematuria that resolved with conservative management. Insufficient data were available to assess the IPSS or IIEF-5 scores. With a short-term follow-up SPPI appears to provide excellent prostate cancer control with an acceptable rate of complications for patients with local recurrence of prostate cancer after EBRT. An extended follow-up is necessary to determine the long-term durability and safety of SPPI.

External-Beam Radiotherapy for Clinically Localized Prostate Cancer in Osaka, Japan, 1995–2006

To establish an initial database of external-beam radiotherapy (EBRT) for clinically localized prostate cancer used in Osaka, Japan, and, by analyzing the results of the Osaka multicenter cooperative study, to determine time trends, outcome, and applicability of existing and the authors' original risk stratification methods. Data of 652 patients with clinically localized prostate cancer (T1-4 N0 M0) were accrued from July to December 2007. These patients had been treated from 1995 through 2006 with consecutive definitive EBRT of > or = 60 Gy at eleven institutions, mainly in Osaka. Altogether, 436 patients were eligible for analysis using several risk stratification methods, namely, those of D'Amico et al., the National Comprehensive Cancer Network (NCCN), and Seattle, as well as the authors' original Prostate Cancer Risk Index (PRIX). The number of patients showed a tenfold increase over 10 years, together with a rapid spread of the use of Gleason Score from 0% to > 90% of cases. The dominant RT dose fractionation was 70 Gy/35 fractions (87%). Hormone therapy had been administered to 95% of the patients and the higher PRIX corresponded to the higher rate of hormone usage. 3- and 5-year biochemical relapse-free survival (bRFS) rates were 85% and 70%, respectively. The D'Amico (p = 0.132), NCCN (p = 0.138), Seattle (p = 0.041) and PRIX (p = 0.044) classifications showed weak or no correlation with bRFS, while the own modified three-class PRIX (PRIX 0, 1-5, 6) showed a strong correlation (p = 0.002). The use of prostate EBRT in Japan is still in its infancy, but is rapidly expanding. The short-term outcomes have been satisfactory considering the moderate RT dose. A very high rate of hormone usage may affect the outcome favorably, but also may compromise the usefulness of current risk stratification.

Paraganglioma of the Head and Neck

Paragangliomas are rare neuroendocrine neoplasms of the head and neck. Treatment strategies include resection, definitive external beam radiation therapy (EBRT), stereotactic radiosurgery (SRS), or observation alone. Due to their rarity and indolent clinical behavior, the optimal management for long-term control is unknown. This Institutional Review Board-approved retrospective study identified all paragangliomas of the head and neck treated with definitive fractionated radiotherapy at Duke University Medical Center from 1963 to 2005 with minimum 2-year follow-up. Local control (LC) was calculated using the Kaplan-Meier method. Thirty-one patients were identified and treated with EBRT (median dose: 54 Gy, range: 38-65 Gy). Twelve patients were treated with megavoltage photon; 19 were treated with either cobalt-60 or cesium-137. Fourteen (45%) had undergone resection preceding radiation. Median follow-up was 9 years (range: 2-35 years), with 10 patients having greater than 15-year follow-up. LC at 5, 10, and 15 years was 96%, 90%, and 90%, respectively. There were no failures in the group treated with megavoltage photons, although this was not statistically significant (P = 0.28). There was no difference in LC between salvage radiation therapy (RT) used after surgical failure and definitive RT alone (10-year LC, 73% vs. 100%, respectively, P = 0.31). The incidence of acute toxicity greater than grade 2 was 3%, and there were no late toxicities greater than grade 2. RT is an effective and well-tolerated treatment for paragangliomas of the head and neck.

Does the Entire Uterus Need to be Treated in Cancer of the Cervix? Role of Adaptive Brachytherapy

To evaluate local control and toxicity by use of a method of adaptive cervical brachytherapy (ACB). From 1998 to 2008, we identified 65 cervical cancer patients with FIGO (International Federation of Gynecology and Obstetrics) Stage IB1-IVA disease who received definitive external beam radiation therapy and high-dose rate brachytherapy with tandem and ovoid applicators. As tumors regressed, 45 of 65 patients had the tandem source retracted from the uterine fundus at successive brachytherapy insertions, thus decreasing the number of (192)Ir dwell positions. Tests of trend and Fisher's exact test were used to identify the effect of ACB on disease control and toxicity. Kaplan-Meier analyses were performed to evaluate disease control and late complications. The median follow-up was 24.5 months. Of the patients, 92% received chemotherapy. The 3-year overall survival, 3-year disease-free survival, 3-year distant metastasis-free survival, and local control rates were 67%, 76%, 79%, and 97%, respectively. There was only 1 isolated local failure, and there were no local failures beyond 1 year. Distant failure was involved in 93% of recurrences. No significant trend was identified regarding the extent of retraction of the tandem source start position with either failure or toxicity. Acute and actuarial 3-year late Grade 3 toxicity or greater occurred in 24.6% and 17% of patients, respectively. ACB determined by clinical response yielded excellent local control rates. These data indicate that ACB may be useful in decreasing late toxicities from high-dose rate brachytherapy. With the advent of three-dimensional image-guided brachytherapy, additional methods to adapt treatment technique to changes in tumor volume warrant investigation.

Biochemical failure after radiation therapy for prostate cancer: Racial differences

e16071 Background: Many guidelines for prostate cancer treatment are based on clinical trials with predominantly white patient (pt) populations. The generalizability of these results assumes similar tumor biology among all races. We set out to examine biochemical failure (PSA failure) rates in a cohort of pts after definitive external beam radiation (EBRT) in the racially diverse population at our institution. Methods: We conducted an IRB-approved retrospective review of pts treated with definitive EBRT from January 2000 to April 2008. We excluded from analysis pts who received brachytherapy, salvage, adjuvant or palliative radiation. Race, country of origin, diagnostic data, pre- and post-treatment PSA, Gleason score (GS), clinical stage (CS), and treatment history were reviewed. CS was based on the original clinician's assessment at time of diagnosis. PSA failures were defined using 1996 ASTRO criteria. Two cohorts were grouped by race: white and nonwhite. Statistical analysis was performed using Fisher's Exact test. Results: One hundred seventy-four pts were treated with definitive EBRT. Forty-four pts were white and 130 were nonwhite. Both cohorts demonstrated similar distributions in GS and CS (see Table ). The white cohort had a high proportion of pts with a pretreatment PSA &lt;10 ng/ml (66%) as compared to the nonwhite cohort (46%). Distribution of race/region of origin is: White 44 (25%), Black-American 78 (45%), Black-Caribbean 28 (16%), Black-African 2 (1%), Hispanic 21 (12%), Asian 1 (1%). Just under 50% of each group received neoadjuvant androgen deprivation therapy. PSA failure rate was 7% for the white cohort and 13% for nonwhite (p = 0.41). Conclusions: In this retrospective analysis, there was no statistical difference among races with regard to PSA failure rates. The PSA and Gleason trends in each cohort were consistent with published data on this topic. Dedicated evaluation of the prognostic value of traditional risk stratification in nonwhite pt populations in a prospective trial is warranted. [Table: see text] No significant financial relationships to disclose.

External Beam Radiotherapy for Prostate Cancer Patients on Anticoagulation Therapy: How Significant is the Bleeding Toxicity?

To characterize the bleeding toxicity associated with external beam radiotherapy for prostate cancer patients receiving anticoagulation (AC) therapy. The study cohort consisted of 568 patients with adenocarcinoma of the prostate who were treated with definitive external beam radiotherapy. Of these men, 79 were receiving AC therapy with either warfarin or clopidogrel. All patients were treated with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy. Bleeding complications were recorded during treatment and subsequent follow-up visits. With a median follow-up of 48 months, the 4-year actuarial risk of Grade 3 or worse bleeding toxicity was 15.5% for those receiving AC therapy compared with 3.6% among those not receiving AC (p < .0001). On multivariate analysis, AC therapy was the only significant factor associated with Grade 3 or worse bleeding (p < .0001). For patients taking AC therapy, the crude rate of bleeding was 39.2%. Multivariate analysis within the AC group demonstrated that a higher radiotherapy dose (p = .0408), intensity-modulated radiotherapy (p = 0.0136), and previous transurethral resection of the prostate (p = .0001) were associated with Grade 2 or worse bleeding toxicity. Androgen deprivation therapy was protective against bleeding, with borderline significance (p = 0.0599). Dose-volume histogram analysis revealed that Grade 3 or worse bleeding was minimized if the percentage of the rectum receiving >or=70 Gy was <10% or the rectum receiving >or=50 Gy was <50%. Patients taking AC therapy have a substantial risk of bleeding toxicity from external beam radiotherapy. In this setting, dose escalation or intensity-modulated radiotherapy should be used judiciously. With adherence to strict dose-volume histogram criteria and minimizing hotspots, the risk of severe bleeding might be reduced.

Interstitial brachytherapy in the management of persistent head and neck disease after definitive external beam radiation therapy

Purpose Persistent disease after definitive external beam radiation therapy for head and neck (H&N) malignancies negatively impacts survival. In this series, the effectiveness of low-dose-rate brachytherapy in the management of persistent H&N disease is explored. Methods All patients who received brachytherapy for persistent H&N disease between 1987 and 2002 were identified. Tumor and treatment characteristics and toxicities were recorded. Progression-free survival and overall survival estimates were generated. The influence of prognostic factors was determined. Results Twelve patients were analyzable. Brachytherapy was given curatively ( n = 4) in patients not amenable to surgery or in combination with surgical dissection to avoid carotid resection ( n = 8). Seven patients had disease progression with a median time to progression of 11 months (95% confidence interval: 0–22.9). The only negative prognostic factor was time to re-treatment (brachytherapy >4 months) after definitive treatment ( p = 0.003). Overall survival at 1 and 5 years was 50% and 21%, respectively. Toxicity was limited to one major complication (fistula) and five minor toxicities: low-grade radionecrosis ( n = 2), cellulitis ( n = 1), and wound dehiscence ( n = 2). Conclusion In patients with persistent disease, brachytherapy is an appealing re-treatment alternative. When combined with neck dissection, brachytherapy yields less morbidity than the surgical alternative of carotid resection.

High-dose-rate brachytherapy for localized prostate adenocarcinoma post abdominoperineal resection of the rectum and pelvic irradiation: Technique and experience

Purpose Treatment options are limited for patients with localized prostate cancer and a prior history of abdominoperineal resection (APR) and pelvic irradiation. We have previously reported on the successful utility of high-dose-rate (HDR) brachytherapy salvage for prostate cancer failing definitive external beam radiation therapy (EBRT). In this report, we describe our technique and early experience with definitive HDR brachytherapy in patients post APR and pelvic EBRT. Patients and Methods Six men with newly diagnosed localized prostate cancer had a prior history of APR and pelvic EBRT. Sixteen to 18 HDR catheters were placed transperineally under transperineal ultrasound–guidance. The critical first two catheters were placed freehand posterior to the inferior rami on both sides of the bulbar urethra under cystoscopic visualization. A template was used for subsequent catheter placement. Using CT-based planning, 5 men received 36 Gy in six fractions as monotherapy. One patient initially treated with EBRT to 30 Gy, received 24 Gy in four fractions. Results Median age was 67.5 (56–74) years. At a median followup of 26 (14–60) months, all patients are alive and with no evidence of disease per the Phoenix definition of biochemical failure, with a median prostate-specific antigen nadir of 0.19 ng/mL. Three men have reported grade 2 late genitourinary toxicity. There has been no report of grade 3–5 toxicity. Conclusion Transperineal ultrasound–guided HDR brachytherapy using the above technique should be considered as definitive therapy for patients with localized prostate cancer and a prior history of APR and pelvic EBRT.

T2-weighted endorectal magnetic resonance imaging of prostate cancer after external beam radiation therapy

To retrospectively determine the accuracy of T2-weighted endorectal MR imaging in the detection of prostate cancer after external beam radiation therapy and to investigate the relationship between imaging accuracy and time since therapy. Institutional review board approval was obtained and the study was HIPPA compliant. We identified 59 patients who underwent 1.5 Tesla endorectal MR imaging of the prostate between 1999 and 2006 after definitive external beam radiation therapy for biopsy-proven prostate cancer. Two readers recorded the presence or absence of tumor on T2-weighted images. Logistic regression and Fisher's exact tests for 2x2 tables were used to determine the accuracy of imaging and investigate if accuracy differed between those imaged within 3 years of therapy (n = 25) and those imaged more than 3 years after therapy (n = 34). Transrectal biopsy was used as the standard of reference for the presence or absence of recurrent cancer. Thirty-four of 59 patients (58%) had recurrent prostate cancer detected on biopsy. The overall accuracy of T2-weighted MR imaging in the detection cancer after external beam radiation therapy was 63% (37/59) for reader 1 and 71% for reader 2 (42/59). For both readers, logistic regression showed no difference in accuracy between those imaged within 3 years of therapy and those imaged more than 3 years after therapy (p = 0.86 for reader 1 and 0.44 for reader 2). T2-weighted endorectal MR imaging has low accuracy in the detection of prostate cancer after external beam radiation therapy, irrespective of the time since therapy.

Salvage Permanent Perineal Radioactive Seed Implantation for the Treatment of Localized Prostate Adenocarcinoma Recurrence after External Beam Radiation

Salvage therapies for recurrences after definitive external beam radiation therapy for localized adenocarcinoma of the prostate are associated with significant morbidity and biochemical failure. We examined our experience with salvage permanent perineal radioactive seed implantation (SPPI) as a possible therapeutic option for recurrent prostate adenocarcinoma. Retrospective analysis was performed on patients who underwent SPPI for localized recurrent prostate adenocarcinoma from 1996 to 2007. Exclusion criteria were patients who underwent primary brachytherapy, radical prostatectomy, or had no follow-up. Primary outcomes were time to biochemical relapse free survival (ASTRO and Phoenix definitions: 3 consecutive PSA rises and PSA nadir +2 ng/mL) and cancer specific survival. Secondary outcomes were IPSS, IIEF5, and complications based upon Common Terminology Criteria for Adverse Events version 3. Thirty-eight patients underwent SPPI during this period. Four and 5 patients were treated with primary brachytherapy or radical prostatectomy, respectively, and an additional 4 patients had inadequate follow-up. Therefore, 13 patients were excluded, leaving a total of 25 patients for analysis. At time of salvage therapy, median PSA was 3.36 ng/mL, median PSA doubling time was 20 months, and all patients were clinically restaged at <T2 with negative transrectal ultrasound and/or MR spectroscopy. Gleason score was 6 in 7 patients, 7 in 10 patients, >8 in 3 patients (not graded in 5 patients). Initial treatment for 23 patients was EBRT, 1 patient EBRT + Proton beam, and 1 patient EBRT + LDR. The median time to the diagnosis of local recurrence was 49 months. In those who underwent SPPI median follow-up was 20 months. Cancer free survival was 96% (1 death); biochemical relapse free survival was 88% (3 patients). PSA was elevated above pre-SPPI levels at 3 months in all three failures, but lower in all 22 patients considered relapse free. Complications entailed 1 urethral stricture, 1 Grade 3 rectal hemorrhage, and 7 Grade 2 gross hematuria that resolved with conservative management. Insufficient data was available to assess IPSS or IIEF5 scores. With short-term follow-up SPPI appears to provide excellent prostate cancer control with an acceptable rate of complications for patients with local recurrence of prostate cancer after EBRT. Extended follow-up is necessary to determine long-term durability and safety of this treatment modality.

Is Androgen Deprivation Beneficial in Patients Undergoing Definitive High Dose External Beam Radiation Therapy for Prostate Cancer?

Is Androgen Deprivation Beneficial in Patients Undergoing Definitive High Dose External Beam Radiation Therapy for Prostate Cancer?

Safety and Immunologic Response of a Viral Vaccine to Prostate-Specific Antigen in Combination with Radiation Therapy when Metronomic-Dose Interleukin 2 Is Used as an Adjuvant

We have previously reported on the safety and immunologic response of a poxvirus-based vaccine encoding prostate-specific antigen (PSA) used in combination with radiation therapy in patients with localized prostate cancer. We hypothesized that a "metronomic" dose of interleukin 2 (IL-2) as a biological adjuvant would cause less toxicity while maintaining immunologic response. Eighteen patients with localized prostate cancer were treated in a single-arm trial using previously established doses of vaccine and radiation therapy. The vaccine used was a recombinant vaccinia virus engineered to encode PSA admixed with a recombinant vaccinia encoding the costimulatory molecule B7.1, followed by booster vaccinations with a recombinant fowlpox vector expressing PSA. Patients received a total of eight planned vaccination cycles, once every 4 weeks, with granulocyte-macrophage colony-stimulating factor given on days 1 to 4 and interleukin 2 (IL-2) at a dose of 0.6 MIU/M2 given from days 8 to 21 after each vaccination. Definitive external beam radiation therapy was initiated after the third vaccination cycle. Patients were evaluated for safety and immunologic response. Toxicity and immunologic activity were compared with the previously reported regimen containing a higher dose of IL-2. Seventeen of 18 patients received all eight cycles of vaccine with IL-2. Five of eight HLA-A2+ patients evaluated had an increase in PSA-specific T cells of > or =3-fold. Toxicities were generally mild, with only seven vaccination cycles of 140 given resulting in grade 3 toxicities possibly attributable to IL-2. Metronomic-dose IL-2 in combination with vaccine and radiation therapy is safe, can induce prostate-specific immune responses, and has immunologic activity similar to low-dose IL-2, with markedly reduced toxicities.

External beam radiotherapy for laryngeal cancer and risk for second primary thyroid carcinoma: A SEER database analysis

17003 Background: Low radiation doses lead to increased rates of second primary cancers of the thyroid. It is unclear whether higher, definitive doses of radiotherapy would have a similar effect on induction of second primary thyroid cancers. We compare the risks of second primary thyroid cancers after treatment for localized laryngeal cancer. Method: The 17-registry Surveillance, Epidemiology, and End Results database was searched for patients with Historic Stage A in situ or localized squamous cell carcinoma of the larynx (T1–2, some T3, N0 M0). Radiotherapy technique for this site and stage would involve a definitive dose to the thyroid immediately adjacent to the larynx. For patients who underwent definitive external beam radiotherapy or definitive resection, the incidence of a new primary thyroid cancer were compared. Results: There were 23,091 cases with in situ or localized disease of the larynx. Of these, 7,988 underwent surgical resection while 15,103 underwent radiotherapy. 30 pathologically confirmed cases of a new thyroid primary occurred at least 2 months after diagnosis of laryngeal carcinoma. 13 of these were originally treated with laryngeal resection only (0.16%), while 17 were originally treated with laryngeal radiation (0.11%). No statistically significant correlation existed between laryngeal radiation and second thyroid cancers. In the group <40 years of age on initial laryngeal cancer diagnosis, 228 patients had been treated with radiation versus 181 treated surgically. Of these, 4 cases in the radiation arm versus no cases in the surgery cohort experienced a second primary thyroid cancer. This was not statistically significant. Of patients who received primary radiotherapy to the larynx, there was a correlation between age <60 and the likelihood of a second thyroid primary (p=.02). Conclusion: There is no overall association between definitive-dose radiotherapy to the larynx and formation of a second primary thyroid cancer. The low overall incidence of such cases and small probability of second primary cancer in the thyroid after radiotherapy to the larynx suggests that this should not determine the ultimate choice regarding radiation versus surgery for early-stage laryngeal cancer. No significant financial relationships to disclose.