Breast cancer patients have better outcomes than prostate cancer patients for palliation of painful bone metastases: Results of RTOG 97–14

Abstract

6073 Background: It is unclear whether there are gender-based differences in pain response and survival after palliative external beam radiotherapy (XRT) for painful bone metastases from breast or prostate cancers. Methods: RTOG and NCCTG conducted a randomized, prospective phase III study of XRT for patients with breast or prostate cancer and painful bone metastases (Brief Pain Index (BPI) worst pain score of ≥5 out of 10). Patients were randomized to 8 Gy in a single fraction vs. 30 Gy in 10 fractions, stratified by number of painful sites, weight bearing site, worst pain score and bisphosphonate usage. Results of the primary study are reported elsewhere; XRT was very effective, providing pain relief in 66% of patients. At 3 months follow-up, there was no difference between the two treatment arms, regardless of stratification. Results: In this gender-based analysis, there were 453 women with breast cancer and 445 men with prostate cancer; median age was 58 and 71 years, respectively. Stratification variables were balanced other than more women received bisphosphonates (46% vs 8% of men). Pain relief was evaluated at 3 months using the BPI. For breast and prostate cancer, complete response was seen in 17% and 16% and partial response in 54% and 43% for an overall response rate of 71% and 59% (p=0.0034) Median survival on the 30 Gy arm for women was 11.6 months compared to 7.3 months for men and median survival on the 8 Gy arm for women was 12.5 months compared to 7.9 months for men. Separate multivariate analyses of the 30 Gy arm and 8 Gy arm, showed that women with breast cancer had statistically significantly longer survival compared to men with prostate cancer (30Gy: HR 1.78, p-value <0.0001; 8Gy: HR 1.75, p-value < 0.0001), after adjusting for age (which was not significant) and KPS. Conclusions: Women with bone metastases from breast cancer experience better outcomes in terms of pain control and survival compared to men with prostate cancer with bone mets treated with palliative radiotherapy. Further consideration should be given to tailoring treatment by gender. Acknowledgment: This trial was supported by NCI grants RTOG U10 CA21661, CCOP U10 CA37422, and Stat U10 CA32115. No significant financial relationships to disclose.