Mesonephric and mesonephric-like adenocarcinomas of gynecologic origin: A single-center experience with molecular characterization, treatment, and oncologic outcomes.

OBJECTIVES: Mesonephric (MA) and mesonephric-like (MLA) adenocarcinomas are rare cancers, and data on clinical behavior and response to therapy are limited. We sought to report molecular features, treatment, and outcomes of MA/MLA from a single institution. METHODS: Patients with MA (cervix) or MLA (uterus, ovary, other) treated at Memorial Sloan Kettering Cancer Center (MSK) from 1/2008-12/2021 underwent pathologic re-review. For patients with initial treatment at MSK, progression-free survival (PFS1) was calculated as time from initial surgery to progression or death; second PFS (PFS2) was calculated as time from start of treatment for recurrence to subsequent progression or death. Overall survival (OS) was calculated for all patients. Images were retrospectively reviewed to determine treatment response. Somatic genetic alterations were assessed by clinical tumor-normal sequencing (MSK-Integrated Mutation Profiling of Actionable Cancer Targets [MSK-IMPACT]). RESULTS: Of 81 patients with confirmed gynecologic MA/MLA, 36 received initial treatment at MSK. Sites of origin included cervix (n = 9, 11%), uterus (n = 42, 52%), ovary (n = 28, 35%), and other (n = 2, 2%). Of the 36 patients who received initial treatment at MSK, 20 (56%) recurred; median PFS1 was 33 months (95% CI: 17-not evaluable), median PFS2 was 8.3 months (95% CI: 6.9-14), and median OS was 87 months (95% CI: 58.2-not evaluable). Twenty-six of the 36 patients underwent MSK-IMPACT testing, and 25 (96%) harbored MAPK pathway alterations. CONCLUSION: Most patients diagnosed with early-stage disease ultimately recurred. Somatic MAPK signaling pathway mutations appear to be highly prevalent in MA/MLA, and therapeutics that target this pathway are worthy of further study.

Patient-Reported Outcome Measures for Patients Who Have Clinical T4 Breast Cancer Treated via Mastectomy with and Without Reconstruction.

BACKGROUND: Patients with clinical T4M0 breast cancer are recommended to undergo neoadjuvant chemotherapy, modified radical mastectomy, and postmastectomy radiotherapy. This study determined whether BREAST-Q scores differ by decision to pursue reconstruction or timing of reconstruction. METHODS: This retrospective, single-institutional study analyzed cT4 breast cancer patients from 2014 to 2021 without evidence of distant metastatic disease undergoing mastectomy with or without reconstruction. As routine care, BREAST-Q was administered preoperatively, then 6 months, 1 year, and 2 years postoperatively. Satisfaction and quality-of-life domains were compared between mastectomy with no reconstruction (NR), immediate reconstruction (IR), and delayed reconstruction (DR) groups. RESULTS: Of the 144 patients eligible for this study, 71 (49%) had NR, 36 (25%) had DR, and 37 (26%) had IR. The patients undergoing reconstruction were younger and more likely to elect contralateral prophylactic mastectomy. Timing of reconstruction was not associated with significant differences in satisfaction with breasts (SATBR) at any time point. For the patients who had DR, breast satisfaction increased over time after reconstructive surgery. Physical well-being of the chest (PWB-CHEST) did not significantly differ among IR, DR, and NR at any time point. The patients who underwent DR experienced improvement in PWB-CHEST scores from preoperative scores. The patients with IR and NR experienced PWB-CHEST decline over time. Psychosocial well-being (PSWB) did not differ significantly across time or by subgroup. CONCLUSIONS: The patients with T4 breast cancer who elected reconstruction did not differ in patient-reported outcomes based on timing of reconstruction. In the DR cohort, SATBR significantly improved after reconstructive surgery. These data can help inform breast reconstructive decision-making for patients facing the choice among DR, IR, and NR.

ASO Visual Abstract: Patient-Reported Outcome Measures in Patients with Clinical T4 Breast Cancer Treated with Mastectomy With and Without Reconstruction.

AIM: Do patient-reported outcome measures differ among clinical T4 patients undergoing mastectomy with and without reconstruction? FINDINGS: Neither reconstruction nor timing of reconstruction were associated with superior outcomes for breast satisfaction, physical well-being of the chest, or psychosocial well-being at any timepoint.

Ancestry testing of "Old Tom," a killer whale central to mutualistic interactions with human whalers.

Cooperative hunting between humans and killer whales (Orcinus orca) targeting baleen whales was reported in Eden, New South Wales, Australia, for almost a century. By 1928, whaling operations had ceased, and local killer whale sightings became scarce. A killer whale from the group, known as "Old Tom," washed up dead in 1930 and his skeleton was preserved. How these killer whales from Eden relate to other populations globally and whether their genetic descendants persist today remains unknown. We extracted and sequenced DNA from Old Tom using ancient DNA techniques. Genomic sequences were then compared with a global dataset of mitochondrial and nuclear genomes. Old Tom shared a most recent common ancestor with killer whales from Australasia, the North Atlantic, and the North Pacific, having the highest genetic similarity with contemporary New Zealand killer whales. However, much of the variation found in Old Tom's genome was not shared with these widespread populations, suggesting ancestral rather than ongoing gene flow. Our genetic comparisons also failed to find any clear descendants of Tom, raising the possibility of local extinction of this group. We integrated Traditional Custodian knowledge to recapture the events in Eden and recognize that Indigenous Australians initiated the relationship with the killer whales before European colonization and the advent of commercial whaling locally. This study rectifies discrepancies in local records and provides new insight into the origins of the killer whales in Eden and the history of Australasian killer whales.

Evaluation of a mobile behavior change program for weight loss in breast cancer survivors.

Post-diagnosis weight gain is common in early-stage breast cancer and is associated with increased risk of recurrence and mortality. Intentional weight loss is difficult to maintain, and digital lifestyle interventions may provide a scalable approach to address this challenge. In this prospective single-arm study (ClinicalTrials.gov NCT04753268; February 15, 2021), key eligibility criteria included: stage I-III breast cancer, body mass index (BMI) ≥ 27.5 kg/m2, and completion of cancer treatment ≥6 months before study enrollment. Participants were provided with a behavioral change mobile application (Noom®). The primary endpoint was a change in self-reported weight from baseline to 26 weeks. Secondary endpoints included engagement, changes in physical activity, dietary patterns, and patient-reported outcomes (PRO). In total, 31 patients were enrolled (mean age 56.8 ± 9.9, mean baseline BMI 33.5 kg/m2 ± 6.5). The mean weight change was -4.8 kg ( ± 4.4, P < 0.001), mean percent weight change was -5.6% ( ± 5.0%); 11/31 patients (35.5%) lost ≥5% of their initial weight. Metrics of digital application engagement associated with weight loss ≥5% included articles read (P = 0.012), weights logged (P = 0.006), food records logged (P = 0.001), messages sent (P = 0.001), and application open count (P = 0.014). Significant increases were seen in mean daily step count (P = 0.004), GPAQ scores (P = 0.002), and Body Image Scale scores (P < 0.001). Mean energy intake remained consistently in a calorie-restricted range of 1300-1400 kcal/day. In this study, breast cancer survivors were highly engaged with a behavioral change smartphone application which led to clinically significant weight loss, increased physical activity, maintenance of an energy-restricted diet, and improvements in body image.

Evolving consolidation patterns and outcomes for a large cohort of primary CNS lymphoma patients.

Consolidation strategies for primary central nervous system lymphoma (PCNSL) after induction chemoimmunotherapy include whole-brain radiotherapy (≤24Gy reduced-dose [RD], >24Gy standard-dose [SD] WBRT) and cytarabine, non-myeloablative chemotherapy (NMC), or autologous hematopoietic cell transplantation (AHCT); however, comparative outcomes are lacking. PCNSL outcomes from 1983-2020 were stratified by decade and MSKCC recursive partitioning analysis (RPA) class. Clinicodemographic associations with consolidation were analyzed by multinomial logistic regression. Progression-free (PFS) and overall survival (OS) were analyzed by proportional hazards from consolidation. Of 559 patients, 385 (69%) were consolidated. Median follow-up and OS were 7.4 and 5.7 years, respectively. WBRT use declined (61% in 1990s vs. 12% in 2010s), while AHCT (4% in 1990s vs. 32% in 2010s) and NMC (27% in 1990s vs. 52% in 2010s) rose. Compared to RPA 1 (age<50), RPA 2 (age≥50, KPS≥70) was more likely to receive NMC. Those with partial response to induction were less likely to receive AHCT (OR 0.36, p=0.02). Among 351 with complete response to consolidation, only receipt of R-MPV induction was associated with improved PFS (HR 0.5, p=0.006). Among RPA 1, median PFS and OS were not reached for AHCT or RD-WBRT, vs. 2.5 and 13.0 years, respectively, after NMC. Among RPA class 3 (KPS<70), median PFS and OS post-RD-WBRT were 4.6 and 10 years, respectively, vs. 1.7 and 4.4 years post-NMC. No significant adjusted survival differences were seen across consolidation strategies. NMC is increasingly used in lieu of RD-WBRT despite a trend toward less favorable PFS. RD-WBRT can be considered in patients ineligible for AHCT.

Echocardiographic Functional Outcomes Following Regional Nodal Irradiation for Breast Cancer Using Volumetric Modulated Arc Therapy.

Purpose: Regional nodal irradiation (RNI) for breast cancer yields improvements in disease outcomes, yet comprehensive target coverage often increases cardiac radiation therapy (RT) dose. Volumetric modulated arc therapy (VMAT) may mitigate high-dose cardiac exposure, although it often increases the volume of low-dose exposure. The cardiac implications of this dosimetric configuration (in contrast to historic 3D conformal techniques) remain uncertain. Methods and Materials: Eligible patients receiving adjuvant RNI using VMAT for locoregional breast cancer were prospectively enrolled in an IRB-approved study. Echocardiograms were performed prior to RT, at the conclusion of RT, and 6 months following RT. Echocardiographic parameters were measured by a single reader and measures were compared pre- and post-RT via the signed-rank test. Changes in echocardiographic parameters over time were compared to mean and max heart doses via the Spearman correlation test. Results: Among 19 evaluable patients (median age 38 years), 89% (n = 17) received doxorubicin and 37% (n = 7) received trastuzumab/pertuzumab combination therapy. All patients received VMAT-based whole-breast/chest wall and RNI. The average mean heart dose was 456 cGy (range, 187-697 cGy) and the average max heart dose was 3001 cGy (1560-4793 cGy). Among salient echocardiographic parameters, no significant decrement in cardiac function was observed when comparing pre-RT to 6 months post-RT: mean left ventricular ejection fraction (LVEF) was 61.8% (SD 4.4%) pre-RT and 62.7% (SD 3.8%) 6 months post-RT (P = .493); mean global longitudinal strain (GLS) was -19.3% (SD 2.2%) pre-RT and -19.6% (SD 1.8%) 6 months post-RT (P = .627). No individual patient exhibited reduced LVEF or sustained decrement in GLS. No correlations were observed for changes in LVEF or GLS when compared to mean or maximum heart doses (P > .1 for all). Conclusions: VMAT for left-sided RNI yielded no significant early decrement in echocardiographic parameters of cardiac function, including LVEF and GLS, within this limited cohort. No patient exhibited significant LVEF changes, and none exhibited sustained decrements in GLS. VMAT may be a reasonable approach to cardiac avoidance in patients requiring RNI, including those receiving anthracyclines and HER2-directed therapy. Larger cohorts with longer follow-ups will be needed to validate these findings.

Surgical outcomes of cytoreductive nephrectomy in patients receiving systemic immunotherapy for advanced renal cell carcinoma.

PURPOSE: The use of systemic immune checkpoint blockade before surgery is increasing in patients with metastatic renal cell carcinoma, however, the safety and feasibility of performing consolidative cytoreductive nephrectomy after the administration of systemic therapy are not well described. PATIENTS AND METHODS: A retrospective review of patients undergoing nephrectomy was performed using our prospectively maintained institutional database. Patients who received preoperative systemic immunotherapy were identified, and the risk of postoperative complications were compared to those who underwent surgery without upfront systemic treatment. Perioperative characteristics and surgical complications within 90 days following surgery were recorded. RESULTS: Overall, we identified 220 patients who underwent cytoreductive nephrectomy from April 2015 to December 2022, of which 46 patients (21%) received systemic therapy before undergoing surgery. Unadjusted rates of surgical complications included 20% (n = 35) in patients who did not receive upfront systemic therapy and 20% (n = 9) in those who received upfront systemic immunotherapy. In our propensity score analysis, there was no statistically significant association between receipt of upfront immunotherapy and 90-day surgical complications [odds ratio (OR): 1.82, 95% confidence interval (CI): 0.59-5.14; P = 0.3]. This model, however, demonstrated an association between receipt of upfront immunotherapy and an increased odds of requiring a blood transfusion [OR: 4.53, 95% CI: 1.83-11.7; P = 0.001]. CONCLUSION: In our cohort, there was no significant difference in surgical complications among patients who received systemic therapy before surgery compared to those who did not receive upfront systemic therapy. Cytoreductive nephrectomy is safe and with low rates of complications following the use of systemic therapy.

Radiation Therapy for Colorectal Liver Metastasis: The Effect of Radiation Therapy Dose and Chemotherapy on Local Control and Survival.

Purpose: Colorectal liver metastases (CLMs) represent a radioresistant histology. We aimed to investigate CLM radiation therapy (RT) outcomes and explore the association with treatment parameters. Methods and Materials: This retrospective analysis of CLM treated with RT at Memorial Sloan Kettering Cancer Center used Kaplan-Meier analysis to estimate freedom from local progression (FFLP), hepatic progression-free, progression-free, and overall survival (OS). Cox proportional hazards regression was used to evaluate association with clinical factors. Dose-response relationship was further evaluated using a mechanistic tumor control probability (TCP) model. Results: Ninety patients with 122 evaluable CLMs treated 2006 to 2019 with a variety of RT fractionation schemes with a median biologically effective dose (α/ß = 10; BED10) of 97.9 Gy (range, 43.2-187.5 Gy) were included. Median lesion size was 3.5 cm (0.7-11.8 cm). Eighty-seven patients (97%) received prior systemic therapy, and 73 patients (81%) received prior liver-directed therapy. At a median follow-up of 26.4 months, rates of FFLP and OS were 62% (95% CI, 53%-72%) and 75% (66%-84%) at 1 year and 42% (95% CI, 32%-55%) and 44% (95% CI, 34%-57%) at 2 years, respectively. BED10 below 96 Gy and receipt of ≥3 lines of chemotherapy were associated with worse FFLP (hazard ratio [HR], 2.69; 95% CI, 1.54-4.68; P < .001 and HR, 2.67; 95% CI, 1.50-4.74; P < .001, respectively) and OS (HR, 2.35; 95% CI, 1.35-4.09; P = .002 and HR, 4.70; 95% CI, 2.37-9.31; P < .001) on univariate analyses, which remained significant or marginally significant on multivariate analyses. A mechanistic Tumor Control Probability (TCP) model showed a higher 2-Gy equivalent dose needed for local control in patients who had been exposed to ≥ 3 lines of chemotherapy versus 0 to 2 (250 ± 29 vs 185 ± 77 Gy for 70% TCP). Conclusions: In a large single-institution series of heavily pretreated patients with CLM undergoing liver RT, low BED10 and multiple prior lines of systemic therapy were associated with lower local control and OS. These results support continued dose escalation efforts for patients with CLM.

Prophylactic Radiation Therapy Versus Standard of Care for Patients With High-Risk Asymptomatic Bone Metastases: A Multicenter, Randomized Phase II Clinical Trial.

PURPOSE: External-beam radiation therapy (RT) is standard of care (SOC) for pain relief of symptomatic bone metastases. We aimed to evaluate the efficacy of radiation to asymptomatic bone metastases in preventing skeletal-related events (SRE). METHODS: In a multicenter randomized controlled trial, adult patients with widely metastatic solid tumor malignancies were stratified by histology and planned SOC (systemic therapy or observation) and randomly assigned in a 1:1 ratio to receive RT to asymptomatic high-risk bone metastases or SOC alone. The primary outcome of the trial was SRE. Secondary outcomes included hospitalizations for SRE and overall survival (OS). RESULTS: A total of 78 patients with 122 high-risk bone metastases were enrolled between May 8, 2018, and August 9, 2021, at three institutions across an affiliated cancer network in the United States. Seventy-three patients were evaluable for the primary end point. The most common primary cancer types were lung (27%), breast (24%), and prostate (22%). At 1 year, SRE occurred in one of 62 bone metastases (1.6%) in the RT arm and 14 of 49 bone metastases (29%) in the SOC arm (P < .001). There were significantly fewer patients hospitalized for SRE in the RT arm compared with the SOC arm (0 v 4, P = .045). At a median follow-up of 2.5 years, OS was significantly longer in the RT arm (hazard ratio [HR], 0.49; 95% CI, 0.27 to 0.89; P = .018), which persisted on multivariable Cox regression analysis (HR, 0.46; 95% CI, 0.23 to 0.85; P = .01). CONCLUSION: Radiation delivered prophylactically to asymptomatic, high-risk bone metastases reduced SRE and hospitalizations. We also observed an improvement in OS with prophylactic radiation, although a confirmatory phase III trial is warranted.

Peripheral Arterial Disease is Associated With Higher Rates of Hospital Encounters and Mortality in Cancer Patients: A Retrospective Study Conducted at a Tertiary Cancer Center.

Cancer and peripheral arterial disease (PAD) have overlapping risk factors and common genetic predispositions. The concomitant effects of PAD and cancer on patients have not been well studied. The objective of this retrospective study is to evaluate outcomes of cancer patients with PAD. A query was made into Memorial Sloan Kettering Cancer Center's database to assess outcome of patients with and without the diagnosis of PAD (using ICD 9 and 10 codes). Inclusion criteria were patients diagnosed with lung, colon, prostate, bladder, or breast cancer between January 1, 2013 and December 12, 2018. A total of 77,014 patients were included in this cohort. 1,426 patients (1.8%, 95% CI 1.8-1.9) carried a diagnosis of PAD. PAD diagnosis was most prevalent in bladder cancer (4.7%, 95% CI 4.1-5.2) and lung cancer patients (4.6%, 95% CI 4.2-4.9). In regression models adjusted for cancer diagnosis, age at cancer diagnosis, stage, diabetes, hyperlipidemia, hypertension, coronary artery disease, cerebrovascular disease, smoking, and BMI > 30, patients with PAD had significantly higher odds of UCC admissions (OR 1.50, 95%CI 1.32-1.70, P < 0.001), inpatient admissions (OR 1.32, 95%CI 1.16-1.50, P < 0.001), and ICU admissions (OR 1.64, 95%CI 1.31-2.03, P < 0.001). After adjusting for all these same factors, patients with PAD had a 13% higher risk of dying relative to patients without PAD (HR 1.13, 95% CI 1.04-1.22, P = 0.003). Cancer patients with PAD had higher risks of ICU stays, UCC visits, inpatient admissions, and mortality compared to cancer patients without PAD even when adjusting for CAD, stroke, other comorbidities, cancer diagnosis, and cancer stage.

Persistence of Telemedicine Usage for Breast and Prostate Cancer after the Peak of the COVID-19 Pandemic.

While COVID-19 catalyzed a shift to telemedicine, little is known about the persistence of remote cancer care in non-emergent times. We assessed telemedicine use at a high-volume academic cancer center in New York City and analyzed breast and prostate cancer visits pre-COVID-19, peak COVID-19, and post-peak. Descriptive statistics assessed visit mode (in person, telemedicine) and type (new, follow-up, other) by department/specialty, with Fisher's exact tests comparing peak/post-peak differences. The study included 602,233 visits, with telemedicine comprising 2% of visits pre-COVID-19, 50% peak COVID-19, and 30% post-peak. Notable variations emerged by department/specialty and visit type. Post-peak, most departments/specialties continued using telemedicine near or above peak levels, except medicine, neurology, and survivorship, where remote care fell. In psychiatry, social work, and nutrition, nearly all visits were conducted remotely during and after peak COVID-19, while surgery and nursing maintained low telemedicine usage. Post-peak, anesthesiology and neurology used telemedicine seldom for new visits but often for follow-ups, while nursing showed the opposite pattern. These trends suggest department- and visit-specific contexts where providers and patients choose telemedicine in non-emergent conditions. More research is needed to explore these findings and evaluate telemedicine's appropriateness and impact across the care continuum.

Regional nodal irradiation for breast cancer using volumetric modulated arc therapy: Echocardiographic functional outcomes.

Introduction: Regional nodal irradiation (RNI) for breast cancer yields improvements in disease outcomes, yet comprehensive target coverage often increases cardiac radiation (RT) dose. Volumetric modulated arc therapy (VMAT) may mitigate high-dose cardiac exposure, although often increases the volume of low-dose exposure. The cardiac implications of this dosimetric configuration (in contrast to historic 3D conformal techniques) remains uncertain. Methods: Eligible patients receiving adjuvant RNI using VMAT for locoregional breast cancer were prospectively enrolled on an IRB-approved study. Echocardiograms were performed prior to RT, at the conclusion of RT, and 6-months following RT. Echocardiographic parameters were measured by a single reader (AY) and measures were compared pre- and post-RT via the Wilcoxon rank sum test. Changes in echocardiographic parameters over time were compared to mean and max heart doses via the Spearman correlation test. Results: Among 19 evaluable patients (median age 38), 89% (n=17) received doxorubicin and 37% (n=7) received trastuzumab/pertuzumab combination therapy. All patients received VMAT-based whole-breast/chest-wall and regional nodal irradiation. Average mean heart dose was 456cGy (range 187-697cGy) and average max heart dose was 3001cGy (1560-4793cGy). Among salient echocardiographic parameters, no significant decrement in cardiac function was observed when comparing pre-RT to 6-months post-RT: mean left ventricular ejection fraction (LVEF) was 61.8 (SD 4.4) pre-RT and 62.7 (SD 3.8) 6-months post-RT (p=0.493); mean global longitudinal strain (GLS) was -19.3 (SD 2.2) pre-RT and -19.6 (SD 1.8) 6-months post-RT (p=0.627). No individual patient exhibited reduced LVEF or sustained decrement in GLS. No correlations were observed for changes in LVEF or GLS when compared to mean or maximum heart doses (p>0.1 for all). Conclusions: VMAT for left-sided RNI yielded no significant early decrement in echocardiographic parameters of cardiac function, including LVEF and GLS. No patient exhibited significant LVEF changes, and none exhibited sustained decrements in GLS. VMAT may be a reasonable approach to cardiac avoidance in patients requiring RNI, including those receiving anthracyclines and HER2-directed therapy. Larger cohorts with longer follow-up will be needed to validate these findings.

Diagnosis of thoracic SMARCA4-deficient undifferentiated tumor in cytology.

INTRODUCTION: Although alterations in SMARCA4-deficient occur in non-small cell lung carcinoma (SD-NSCLC), thoracic SMARCA4-deficient undifferentiated tumor (TSDUT) is recognized as a distinct entity in the 2021 World Health Organization Classification of Thoracic Tumors because of unique morphologic, immunophenotypic and molecular features, and worse survival compared with SD-NSCLC. Cytologic diagnosis of TSDUT is clinically important because of its aggressive behavior and because it is often diagnosed by fine-needle aspiration because TSDUTs are usually unresectable at presentation. Here, we identify cytologic features that can be used for recognition of TSDUT and distinction from SD-NSCLC. MATERIALS AND METHODS: Cytomorphologic features were investigated in cytology specimens from patients with TSDUT (n = 11) and compared with a control group of patients with SD-NSCLC (n = 20). RESULTS: The presence of classic rhabdoid morphology, at least focally, was entirely specific for TSDUT (n = 6, 55%) compared with SD-NSCLC (n = 0) in this study. TSDUT more frequently showed tumor necrosis (n = 11, 100% vs. n = 8, 40%; p = .001), dominant single-cell pattern on aspirate smears or touch preparation slides (n = 8 [of 9], 80% vs. n = 3, 15%; p = .010), nuclear molding (n = 5, 45% vs. n = 1, 5%; p = .013), and indistinct cell borders (n = 11, 100% vs. n = 5, 25%; P < .001) compared with SD-NSCLC, respectively. CONCLUSIONS: Cytomorphologic features occurring more frequently in TSDUT include tumor necrosis, dominant single-cell pattern, nuclear molding indistinct cell borders, and focal rhabdoid cells. Presence of these features in a cytology specimen of an undifferentiated tumor, particularly in a patient with a thoracic mass, should raise suspicion for TSDUT and prompt appropriate ancillary workup.

Osteoradionecrosis of the Jaw Following Proton Radiation Therapy for Patients With Head and Neck Cancer.

Importance: Proton radiation therapy (PRT) has reduced radiation-induced toxic effects, such as mucositis and xerostomia, over conventional photon radiation therapy, leading to significantly improved quality of life in patients with head and neck cancers. However, the prevalence of osteoradionecrosis (ORN) of the jaw following PRT in these patients is less clear. Objective: To report the prevalence and clinical characteristics of ORN in patients with oral and oropharyngeal cancer (OOPC) treated with PRT. Design, Setting, and Participants: This case series reports a single-institution experience (Memorial Sloan Kettering Cancer Center, New York, New York) between November 2013 and September 2019 and included 122 radiation therapy-naive patients with OOPC treated with PRT. Data were analyzed from 2013 to 2019. Main Outcomes and Measures: Clinical parameters, including sex, age, comorbidities, tumor histology, concurrent chemotherapy, smoking, comorbidities, and preradiation dental evaluation, were obtained from the medical record. Patients with clinical or radiographic signs of ORN were identified and graded using the adopted modified Glanzmann and Grätz grading system. Characteristics of ORN, such as location, clinical presentation, initial stage at diagnosis, etiology, time to diagnosis, management, and clinical outcome at the last follow-up, were also collected. Results: Of the 122 patients (mean [SD] age, 63 [13] years; 45 [36.9%] women and 77 [63.1%] men) included in this study, 13 (10.6%) developed ORN following PRT during a median (range) follow-up time of 40.6 (<1-101) months. All patients had spontaneous development of ORN. At the time of initial diagnosis, grade 0, grade 1, grade 2, and grade 3 ORN were seen in 2, 1, 9, and 1 patient, respectively. The posterior ipsilateral mandible within the radiation field that received the full planned PRT dose was the most involved ORN site. At a median (range) follow-up of 13.5 (0.2-58.0) months from the time of ORN diagnosis, complete resolution, stable condition, and progression of ORN were seen in 3, 6, and 4 patients, respectively. The 3-year rates of ORN and death in the total cohort were 5.2% and 21.5%, while the 5-year rates of ORN and death were 11.5% and 34.4%, respectively. Conclusions and Relevance: In this case series, the prevalence of ORN following PRT was found to be 10.6%, indicating that ORN remains a clinical challenge even in the era of highly conformal PRT. Clinicians treating patients with OOPC with PRT should be mindful of this complication.