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Introduction Anti-osteoclast treatment with denosumab or zoledronate is known to effectively reduce the need for radiotherapy to bone and other skeletal-related events (SREs) in patients with metastatic castration-resistant prostate cancer (mCRPC). In this study, we analyze primary versus secondary initiation of bone-targeting agents (BTAs) relative to first palliative bone radiotherapy in patients dying of mCRPC. Methods Provincial administrative databases from Ontario, Canada identified patients with prostate cancer (2007-2018, n  = 98 646) who received continuous androgen deprivation therapy (n  = 29 453), died of prostate cancer (2013-2018, n  = 3864), and received life-prolonging therapy for mCRPC (n  = 1850). Variables were collected looking back 3 years from death. Multivariable analysis explored the relationship between clinical variables and BTAs. Results Of the 58% (1066/1850) patients with mCRPC who received BTA, only 289 (25.4%) started BTA prior to first palliative bone radiotherapy as primary prevention. Eight hundred and forty-eight (74.6%) patients either never received BTA before death (n  = 447) or started BTA only after first bone radiotherapy (n  = 401). More patients received denosumab (n  = 825, 77%) than zoledronic acid (n  = 241, 23%). 51.2% (582/1137) of palliative bone radiotherapy was initiated in the last 12 months of life. Factors associated with the use of BTA included elevated alkaline phosphatase (OR = 1.0, P  = .023), de novo metastases (OR = 1.4, P  = .005), medical oncologist involvement (OR = 2.0, P  = .007), diagnosis 2012-2017 versus 2007-2011 (OR = 0.75, P  = .034), and academic center (OR = 0.061, P  = .007). Conclusion A majority of patients with mCRPC never receive BTAs prior to first SRE, despite universal access and availability of these agents in Ontario. These results highlight an opportunity to improve outcomes by emphasizing early introduction of BTA in patients with mCRPC being started on systemic therapy. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the association of primary tumor volume (TV) with overall survival (OS) and disease‐free survival (DFS) in T3 N0‐3M0 supraglottic cancers treated with intensity‐modulated radiotherapy (IMRT). Methods: This was a retrospective cohort study involving 239 patients diagnosed with T3 N0‐3M0 supraglottic cancers between 2002 and 2018 from seven regional cancer centers in Canada. Clinical data were obtained from the patient records. Supraglottic TV was measured by neuroradiologists on diagnostic imaging. Kaplan–Meier method was used for survival probabilities, and a restricted cubic spline Cox proportional hazards regression analysis was used to analyze TV associations with OS and DFS. Results: Mean (SD) of participants was 65.2 (9.4) years; 176 (73.6%) participants were male. 90 (38%) were N0, and 151 (64%) received concurrent systemic therapy. Mean TV (SD) was 11.37 (12.11) cm3. With mean follow up (SD) of 3.28 (2.60) years, 2‐year OS was 72.7% (95% CI 66.9%–78.9%) and DFS was 53.6% (47.4%–60.6%). Increasing TV was associated (per cm3 increase) with worse OS (HR, 1.01, 95% CI 1.00–1.02, p < 0.01) and DFS (HR, 1.01, 95% CI 1.00–1.02, p = 0.02). Conclusions: Increasing primary tumor volume is associated with worse OS and DFS in T3 supraglottic cancers treated with IMRT, with no clear threshold. The findings suggest that patients with larger tumors and poor baseline laryngeal function may benefit from upfront laryngectomy with adjuvant radiotherapy. [ABSTRACT FROM AUTHOR]

Background: The objective of this study was to examine the utility of postoperative radiation for low and intermediate grade cancers of the parotid and submandibular glands. Methods: The authors conducted a retrospective, Canadian‐led, international, multi‐institutional analysis of a patient cohort with low or intermediate grade salivary gland cancer of the parotid or submandibular gland who were treated from 2010 until 2020 with or without postoperative radiation therapy. A multivariable, marginal Cox proportional hazards regression analysis was performed to quantify the association between locoregional recurrence (LRR) and receipt of postoperative radiation therapy while accounting for patient‐level factors and the clustering of patients by institution. Results: In total, 621 patients across 14 tertiary care centers were included in the study; of these, 309 patients (49.8%) received postoperative radiation therapy. Tumor histologies included 182 (29.3%) acinic cell carcinomas, 312 (50.2%) mucoepidermoid carcinomas, and 137 (20.5%) other low or intermediate grade primary salivary gland carcinomas. Kaplan–Meier LRR‐free survival at 10 years was 89.0% (95% confidence interval [CI], 84.9%–93.3%). In multivariable Cox regression analysis, postoperative radiation therapy was independently associated with a lower hazard of LRR (adjusted hazard ratio, 0.53; 95% CI, 0.29–0.97). The multivariable model estimated that the marginal probability of LRR within 10 years was 15.4% without radiation and 8.8% with radiation. The number needed to treat was 16 patients (95% CI, 14–18 patients). Radiation therapy had no benefit in patients who had early stage, low‐grade salivary gland cancer without evidence of nodal disease and negative margins. Conclusions: Postoperative radiation therapy may reduce LLR in some low and intermediate grade salivary gland cancers with adverse features, but it had no benefit in patients who had early stage, low‐grade salivary gland cancer with negative margins. This was a retrospective, Canadian‐led, international, multi‐institutional analysis of 621 patients with low or intermediate grade salivary gland cancer of the parotid or submandibular gland, of whom 309 patients (49.8%) received postoperative radiation therapy. In regression analysis, postoperative radiation therapy was an independent protective factor against locoregional recurrence with an adjusted hazard ratio of 0.53 (95% confidence interval, 0.29–0.97). [ABSTRACT FROM AUTHOR]