Is Radiation a Good Decision?
The ability of radiation therapy (RT) to lower risk for local breast cancer recurrence (LR) after breast-conserving surgery is disputable. Even though it is highly recommended and most commonly performed, a recent study titled, “Is Radiotherapy Unnecessary for Some Breast Cancer Patients?” revealed some startling information. Some breast cancer types actually have a near four fold increase in cancer reoccurrence should radiation be performed. For example, prior reports have suggested that patients with luminal A molecular subtype tumors — defined as estrogen receptor (ER)-positive, progesterone receptor (PR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, low proliferative rate, and low-to-intermediate nuclear grade — may have such a low baseline risk for LR that RT is unnecessary. So, is radiation a good idea?
To examine this issue further, investigators conducted a reanalysis of the Toronto–British Columbia (TBC) trial (N Engl J Med 2004; 351:963) involving 769 women aged ≥50 with an invasive axillary node–negative adenocarcinoma (≤5 cm) who were randomized to tamoxifen with or without RT after lumpectomy. The researchers performed immunohistochemical analysis of six biomarkers (ER, PR, HER2, cytokeratin 5/6, epidermal growth factor receptor, and Ki-67) on 501 tumor samples, of which 265 were molecular subtype luminal A, 165 were luminal B, and 71 were high-risk (luminal-HER2, HER2-enriched, basal-like, or triple-negative nonbasal).
Rates of 10-year LR were 5.2% for luminal A, 10.5% for luminal B, and 21.3% for high-risk tumors. The interaction between tumor subtype and treatment was not significant. Luminal A patients with low-risk clinical features (age >60, T1 stage, grade 1 or 2 histology) had a 10-year LR rate of 1.3% with tamoxifen alone versus 5.0% with tamoxifen plus RT.
What does this mean?
- Breast cancer patients that are estrogen receptor (ER)-positive, progesterone receptor (PR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, low proliferative rate, and low-to-intermediate nuclear grade should reconsider RT use.
- Radiation therapy for breast cancer may actually INCREASE reoccurrence rates.