How breast cancer responds to early chemotherapy may someday help doctors decide the need for radiation therapy based on individuals’ risk of recurrence, a study showed.
In a combined analysis of two neoadjuvant chemotherapy studies, researchers explored possible predictors of nearby breast cancer recurrence and the use of radiation therapy after mastectomy and lumpectomy.
Neoadjuvant chemotherapy is sometimes given before surgery to shrink tumors and make them easier to remove. Researchers believe a tumor’s response to neoadjuvant chemotherapy may help determine the need for radiation therapy after surgery, allowing for more personalized treatment.
The investigators wanted to find out what characteristics participants shared that might have predicted risk of locoregional recurrence at 10 years of follow-up, and what those traits showed about the impact of neoadjuvant chemotherapy on the need for radiation therapy. Locoregional recurrence is cancer that comes back in the breast or nearby lymph nodes.
Together, the studies provided data on 3,088 participants who had chemotherapy before lumpectomy or mastectomy. Follow-up data was collected to 10 years to keep information balanced between studies. Patterns in participant age, tumor size, presence and number of positive lymph nodes, as well as tumor response to neoadjuvant chemotherapy, were investigated.
The women in this analysis received four courses of Adriamycin and cyclophosphamide (AC) chemotherapy in 21-day cycles before surgery or four courses of AC followed by four courses of docetaxel (Taxotere) in 21-day cycles before surgery. Women treated with mastectomy were not treated with radiation; women who had a lumpectomy received radiation after surgery.
This study represents the largest group available for analysis treated with neoadjuvant chemotherapy and with study-specific radiation therapy.
Taken together, 335 people in the two trials had a locoregional recurrence within 10 years. Of those
- 12.6 percent of 1,947 treated with mastectomy, without radiation treatment, had a recurrence
- 10.3 percent of 1,100 treated with lumpectomy, followed by radiation therapy, had a recurrence
- People who achieved pathologic complete response, or who showed no evidence of invasive breast cancer after neoadjuvant chemotherapy and surgery, no matter which surgery they received, had the lowest risk of recurrence
The researchers suggest that because the risk of recurrence was lowest when neoadjuvant chemotherapy led to a pathologic complete response, regardless of surgery, it may be possible to predict the value of giving radiation treatment.
For example, being older, having a small tumor and reaching pathologic complete response were all found to be related to a lower risk of recurrence. If a woman fit all three of these categories, she would likely have a very low risk of recurrence, and might not need radiation therapy. On the other hand, a woman who only fit two of those three categories might benefit from radiation therapy in addition to her other treatments.
The investigators created two mathematical formulas, one for women treated with lumpectomy and one for women treated with mastectomy, which used the risk factors identified in this study to predict risk of recurrence.
What This Means for You
These findings represent the start of a better understanding of how to predict who benefits most from radiation therapy. If you are newly diagnosed and working with your doctors to create a treatment plan, talk with your surgeon, medical oncologist and radiation oncologist about the risks and benefits of radiation therapy.
It is important to know that these findings may not immediately affect treatment decisions. More studies are needed before the risk-prediction formulas can be accepted as accurate and dependable. New clinical trials are already scheduled to continue this research.
If neoadjuvant chemotherapy is part of your treatment plan, talk with your doctors about how they will evaluate your need for radiation therapy.
Mamounas, EP, Anderson, SJ, Dignam, JJ, et al. Predictors of locoregional recurrence after neoadjuvant chemotherapy: results from combined analysis of National Surgical Adjuvant Breast and Bowel Project B-18 and B-27. Journal of Clinical Oncology. 2012;30(32):3960-3966.