08 Sep Breast Cancer: Long-term Prognostic Factors in the Boost vs No Boost Trial
MedicalResearch.com Interview with:
Conny Vrieling, M.D., Ph.D.
Clinique des Grangettes
MedicalResearch.com: What is the background for this study?
Response: In the early ’90s, the EORTC (European Organisation for Research and Treatment of Cancer) ran the “boost no-boost” trial, randomizing 5569 early-stage breast cancer patients, treated with breast-conserving surgery and whole-breast irradiation, between no boost and a 16-Gy boost. A third of the patients were included in a central pathology review. The 10-year follow-up results of this subpopulation showed that young age and high-grade invasive carcinoma were the most important risk factors for ipsilateral breast tumor recurrence (IBTR).
In this study, we re-analyzed with long-term follow-up the pathological prognostic factors related to IBTR, with a special focus on the evolution of these effects over time.
MedicalResearch.com: What are the main findings?
Response: This time we found that young age and the presence of DCIS adjacent to the invasive tumor were associated with an increased incidence of IBTR, whereas the grade of the invasive tumor was not a significant factor anymore. Looking more in detail to the impact over time of adjacent DCIS and the grade of invasive tumor, we found that high-grade tumors relapsed more frequently only during the first 5 years, whereas the relative effect of age and presence of DCIS was stable over time.
The 20-year cumulative incidence of IBTR was 34% for patients 40 years or younger, compared to 11% for patients 50 years and older. The IBTR incidence was 18% and 9% for tumors with and without DCIS. In the high-risk population (patients ≤ 50 years with DCIS present), a radiotherapy boost dose of 16 Gy reduced the 20-year cumulative incidence of IBTR from 31% to 15% (HR=0.37, p<0.001).
MedicalResearch.com: What should readers take away from your report?
Response: Patients with high-grade invasive tumors should be monitored closely especially in the first 5 years. The impact of DCIS seemed to remain constant over time, indicating that long-term follow-up is necessary for these patients. The boost significantly reduces IBTR in the high-risk population of young patients with DCIS adjacent to the invasive tumor.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: We know that IBTR rates have fallen greatly in the last years, so the absolute risk reduction caused by the boost is currently probably smaller. These factors should be reanalyzed in recent studies to quantify their impact on IBTR in the current context. These results also underline the importance of long-term trial follow-up to estimate absolute effects accurately.
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
Harry Bartelink, MD, PhD et al. Prognostic Factors For Local Control in Breast Cancer After Long-term Follow-up in the EORTC Boost vs No Boost Trial: A Randomized Clinical Trial. JAMA Oncol., September 2016 DOI:10.1001/jamaoncol.2016.3031
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