Radiation therapy can reduce locoregional recurrence and increase survival in T1–2 N1 invasive breast cancer patients presenting with negative estrogen receptor status and presence of lymphovascular invasion, found a study published June 1 in the International Journal of Radiation Oncology*Biology *Physics.
Lead author Po Sheng Yang, MD, from the department of surgery at the Sun Yat-Sen Cancer Center in Taipei, Taiwan, and colleagues sought to define a subgroup of patients at high risk of locoregional recurrence who might be benefit from postmastectomy radiotherapy.
The researchers noted that while prior studies have evaluated radiotherapy following mastectomy in breast cancer patients with larger tumors and four or more positive lymph nodes, this treatment method for smaller tumors (less than 5 cm) with one to three positive lymph nodes (T1-2 N1) remains unknown.
The researchers retrospectively reviewed the cases of 544 patients with T1–2 N1 invasive breast cancer who were treated with modified radical mastectomy between April 1991 and December 2005. Of the 544 patients, 70.4 percent had no radiotherapy and 29.6 percent underwent radiotherapy.
After an average follow-up period of 40 months, the authors found that locoregional recurrence occurred in 7.4 percent of the 544 study patients. High nuclear grade, negative estrogen receptor status, presence of lymphovascular invasion and no subsequent radiation treatments were factors associated with a significantly higher rate of locoregional recurrence, they wrote.
Yang and colleagues noted that radiotherapy reduced the chance of locoregional recurrence in patients younger than 40 years, T2 stage, high nuclear-grade, negative estrogen receptor status and presence of lymphovascular invasion. In addition, radiotherapy was found to reduce locoregional recurrence from 40 percent to 12.5 percent with negative estrogen receptor status and positive lymphovascular invasion. In this patient population, the five-year overall survival increased from 43.7 percent to 87.1 percent.
"Even though the study sample size was small, we feel that the results are compelling," concluded the researchers. "Based on this study, we strongly suggest that radiation therapy be used after mastectomy for this particular group of breast cancer patients."