14 Aug Radiation of Internal Mammary Nodes May Have Small Breast Cancer Survival Benefit
MedicalResearch.com Interview with:
Philip M.P. Poortmans PhD MD
Head of Department, Radiation Oncology
Radboud university medical center
Medical Research: What is the background for this study?
Dr. Poortmans: Based on the former hypothesis that breast cancer sequentially spreads from breast to lymph nodes and from there to distant organs, up to the eighties it was very custom to perform extended radical surgery and to irradiate extensively locoregional for most patients. With the growing interest in systemic treatments to prevent development (= from already present undetectable cancer cells to really visible and threatening metastases) of distant metastases, new information about possible late side effects and our increasing knowledge about the biological behaviour of breast cancer in the eighties and the nineties, the extend of especially locoregional treatment was gradually reduced. For radiation therapy, often the irradiation of the internal mammary lymph nodes was left aside, as this was linked to the delivery of radiation dose to the heart, possibly or probably leading to late side effects. At the start of the study, about half of the radiation oncology departments did include irradiation of the internal mammary lymph nodes in patients with risk factors, while the other half did not. Hereby we had an ideal base for the investigation of the value of treating the non-operated part of the regional lymph nodes.
Medical Research: What are the main findings?
Dr. Poortmans: We found a decreased risk for development of distant metastases of 3% at 10 years, translated in a 3% overall improved overall disease free survival. Up to now, It leads to an improvement of 1.6% in overall survival at 10 years, which is, in contrast to the earlier 2 findings, just not statistically significant (borderline at p = 0.06). On the other hand, breast cancer related mortality is significantly improved and we did not see an increase in non breast cancer related causes of death. Overall toxicity was limited with only a significant increase in pulmonary toxicity, however to a low grade in the big majority of those patients. The benefit in overall survival is in a similar order of magnitude than adding for example taxanes to anthracycline-based adjuvant chemotherapy for a similar patient population as ours.
Medical Research: What should clinicians and patients take away from your report?
First, we should appreciated that the regional (lymph node) recurrence rate is a poor endpoint for evaluation of also locoregional treatment. This can be explained by the fact that once distant metastases are found, no further search for local (breast) or regional (lymph nodes) recurrences is performed any more, as this is not relevant anymore for treatment or prognosis. However, the spread of distant metastases might occur from cancer involvement of the lymph nodes, explaining why we saw the effect of the lymph node irradiation basically only on the rate of development of distant metastases.
As a second message, we can appreciate that the 3% decreased distant metastases rate did not yet fully translate into a survival benefit, which can be explained by the need for even longer follow-up than 10 years. The explanation lies simply in the fact that even after development of distant metastases, patients can live for quite some more years with, however, only very little chance for definitive cure.
Thirdly, we demonstrated with the quality assurance program linked to this trial that radiation treatment as used those days (the accrual phase was from 1996 until January 2004) radiation therapy techniques should be nowadays considered as suboptimal with a lack of full coverage of the target volumes and delivery of a too high dose to the organs at risk. With modern techniques, we expect that the results will even be quite better.
And finally, that the overall outcome of breast cancer improved a lot: at the start of the trial, we estimated overall survival at 10 years being 50%, which we revised in 2000 to 75% and we ended up with more than 80%. Thereby, it becomes more of a challenge to demonstrate benefits of further improving treatment as the same relative improvement will be translated into a lower absolute improvement. Nevertheless, by more effectively preventing the development of distant metastases by improved systemic therapy (or even better by earlier detection with a lower basal rate of distant metastases) the importance of optimizing locoregional control becomes even higher.
Medical Research: What recommendations do you have for future research as a result of this study?
- First of all we have to improve our ability to define which patients will gain most from this treatment.
- Secondly, we have to further investigate how to optimize the technical aspects of this loco regional treatment and …
- Thirdly how to optimally integrate all treatment aspects including locoregional ones and systemic ones.
- Based on all this, we can develop and then provide the patients with shared decision making tools.
Internal Mammary and Medial Supraclavicular Irradiation in Breast Cancer
Philip M. Poortmans, Ph.D., Sandra Collette, M.Sc., Carine Kirkove, Ph.D., Erik Van Limbergen, Ph.D., Volker Budach, Ph.D., Henk Struikmans, Ph.D., Laurence Collette, Ph.D., Alain Fourquet, Ph.D., Philippe Maingon, M.D., Mariacarla Valli, M.D., Karin De Winter, M.D., Simone Marnitz, M.D., Isabelle Barillot, Ph.D., Luciano Scandolaro, M.D., Ernest Vonk, M.D., Carla Rodenhuis, Ph.D., Hugo Marsiglia, Ph.D., Nicola Weidner, Ph.D., Geertjan van Tienhoven, Ph.D., Christoph Glanzmann, Ph.D., Abraham Kuten, M.D., Rodrigo Arriagada, M.D., Harry Bartelink, Ph.D., and Walter Van den Bogaert, Ph.D. for the EORTC Radiation Oncology and Breast Cancer Groups
N Engl J Med 2015; 373:317-327
July 23, 2015 DOI: 10.1056/NEJMoa1415369
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Philip M.P. Poortmans PhD MD (2015). Radiation of Internal Mammary Nodes May Have Small Breast Cancer Survival Benefit MedicalResearch.com