Pharyngeal Constrictor Dose-Volume Histogram Metrics and Patient-Reported Dysphagia in Head and Neck Radiotherapy.

AIMS: Head and neck radiotherapy long-term survival continues to improve and the management of long-term side-effects is moving to the forefront of patient care. Dysphagia is associated with dose to the pharyngeal constrictors and can be measured using patient-reported outcomes to evaluate its effect on quality of life. The aim of the present study was to relate pharyngeal constrictor dose-volume parameters with patient-reported outcomes to identify prognostic dose constraints. MATERIALS AND METHODS: A 64-patient training cohort and a 24-patient testing cohort of oropharynx and nasopharynx cancer patients treated with curative-intent chemoradiotherapy were retrospectively examined. These patients completed the MD Anderson Dysphagia Inventory outcome survey at 12 months post-radiotherapy to evaluate late dysphagia: a composite score lower than 60 indicated dysphagia. The pharyngeal constrictor muscles were subdivided into four substructures: superior, middle, inferior and cricopharyngeal. Dose-volume histogram (DVH) metrics for each of the structure combinations were extracted. A decision tree classifier was run for each DVH metric to identify dose constraints optimising the accuracy and sensitivity of the cohort. A 60% accuracy threshold and feature selection method were used to ensure statistically significant DVH metrics were identified. These dose constraints were then validated on the 24-patient testing cohort. RESULTS: Existing literature dose constraints only had two dose constraints performing above 60% accuracy and sensitivity when evaluated on our training cohort. We identified two well-performing dose constraints: the pharyngeal constrictor muscle D63% < 55 Gy and the superior-middle pharyngeal constrictor combination structure V31Gy < 100%. Both dose constraints resulted in ≥73% mean accuracy and ≥80% mean sensitivity on the training and testing patient cohorts. In addition, a pharyngeal constrictor muscle mean dose <57 Gy resulted in a mean accuracy ≥74% and mean sensitivity ≥60%. CONCLUSION: Mid-dose pharyngeal constrictor muscle and substructure combination dose constraints should be used in the treatment planning process to reduce late patient-reported dysphagia.

Active treatment in low-risk prostate cancer: a population-based study.

Background: Active surveillance instead of active treatment (at) is preferred for patients with low-risk prostate cancer (lr-pca), but practice varies widely. We conducted a population-based study to assess the proportion of patients who underwent at between January 2011 and December 2014, and to evaluate factors associated with at. Methods: The provincial cancer registry was linked to administrative health datasets to identify patients with lr-pca and to acquire demographic, tumour, and treatment data. The primary outcome was receipt of at during the first 12 months after diagnosis, defined as any receipt of external-beam radiotherapy, brachytherapy, radical prostatectomy, cryotherapy, or androgen deprivation. Univariate and multivariate logistic regression were used to analyze the correlation between patient and tumour factors and at. Results: Of 1565 patients with lr-pca, 554 (35.4%) underwent at within 12 months of diagnosis. Radical prostatectomy was the most common treatment (58%), followed by brachytherapy (29.6%). Younger age [odds ratio (or) 0.92; 95% confidence interval (ci): 0.91 to 0.94], lower score (≥3) on the Charlson comorbidity index (OR: 0.36; 95% ci: 0.19 to 0.68), T2 stage (or: 3.05; 95% ci: 2.03 to 4.58), higher prostate-specific antigen (psa) at diagnosis (or: 1.13; 95% ci: 1.06 to 1.21), radiation oncologist consultation (or: 3.35; 95% ci: 2.55 to 4.39), and earlier diagnosis year (2012 or: 0.46; 95% ci: 0.34 to 0.63; 2013 or: 0.45; 95% ci: 0.32 to 0.63; 2014 or: 0.33; 95% ci: 0.23 to 0.47) were associated with a higher probability of at. Conclusions: This contemporary population-based study demonstrates that approximately one third of patients with lr-pca undergo at. Patients of younger age, with less comorbidity, a higher tumour stage, higher psa, earlier year of diagnosis, and radiation oncologist consultation were more likely to undergo at. Further investigation is needed to identify strategies that could minimize overtreatment.

Prostate-specific Antigen Bounce After Stereotactic Body Radiotherapy for Prostate Cancer: A Pooled Analysis of Four Prospective Trials.

AIMS: We conducted a pooled analysis of four prospective stereotactic body radiotherapy (SBRT) trials of low- and intermediate-risk prostate cancer to evaluate the incidence of prostate-specific antigen (PSA) bounce and its correlation with the time-dose-fraction schedule. The correlation between bounce with PSA response at 4 years (nadir PSA < 0.4 ng/ml) and biochemical failure-free survival (BFFS) was also explored. MATERIALS AND METHODS: The study included four treatment groups: 35 Gy/five fractions once per week (QW) (TG-1; n = 84); 40 Gy/five fractions QW (TG-2; n = 100); 40 Gy/five fractions every other day (TG-3; n = 73); and 26 Gy/two fractions QW (TG-4; n = 30). PSA bounce was defined as a rise in PSA by 0.2 ng/ml (nadir + 0.2) or 2 ng/ml (nadir + 2.0) above nadir followed by a decrease back to nadir. Patients with fewer than three follow-up PSA tests were excluded from the pooled analysis. RESULTS: In total, 287 patients were included, with a median follow-up of 5.0 years. The pooled 5-year cumulative incidence of bounce by nadir + 2.0 was 8%. The 2-year cumulative incidences of PSA bounce by nadir + 0.2 were 28.9, 21, 19.6 and 16.7% (P = 0.12) and by nadir + 2.0 were 7.2, 8, 2.7 and 6.7% (P = 0.32) for TG-1 to TG-4, respectively. Multivariable analysis revealed that for nadir + 2.0, pre-treatment PSA (odds ratio 0.49; 95% confidence interval 0.26-0.97) correlated with PSA bounce. Although PSA bounce by nadir + 0.2 (odds ratio 0.10; 95% confidence interval 0.04-0.24) and nadir + 2.0 (odds ratio 0.29; 95% confidence interval 0.09-0.93) was associated with a lower probability of PSA response at 4 years, there was no association between bounce by nadir + 0.2 (hazard ratio 0.36; 95% confidence interval 0.08-1.74) or nadir + 2 (hazard ratio 1.77; 95% confidence interval 0.28-11.07) with BFFS. CONCLUSION: The incidence of PSA bounce was independent of time-dose-fraction schedule for prostate SBRT. One in 13 patients experienced a bounce high enough to be misinterpreted as biochemical failure, and clinicians should avoid early salvage interventions in these patients. There was no association between PSA bounce and BFFS.