Partial breast radiotherapy was noninferior to whole breast radiotherapy in regard to local recurrence in women with low-risk early breast cancer. This research was presented at the 10th European Breast Cancer Conference.1
Though radiotherapy to the whole breast is standard treatment after breast-conserving surgery for women with early breast cancer, it causes changes in the appearance of the breast, often making it firmer and tender to the touch and leading to psychological distress.
“So we considered it important to set up a trial to answer the question: is full dose radiotherapy to whole breast needed in patients with low risk early breast cancer?” said Charlotte Coles, MD, consultant clinical oncologist at Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom. “One group of women received standard full dose radiotherapy to the whole breast. A second group received standard full dose to breast tissue closest to where the lump appears and a slightly lower dose further away. A third group received standard full dose radiotherapy to breast tissue closest to where the lump appears but no radiotherapy dose apart from this.
“We found after 5 years that rates of local relapse (the reappearance of a cancer after treatment in the breast where it was originally detected) were very low in all treatment groups, including those receiving less radiotherapy. Moderate and marked changes in normal breast tissue were also low across all groups. Follow-up is ongoing and 10-year local recurrence rates will be reported at a later stage,” she said.
Recruited from 30 radiotherapy centers across the United Kingdom, this study included 2018 patients older than 50 years (average age, 63 years) who underwent breast conservation surgery for invasive early breast cancer tumors measuring less than 3 cm at their largest point. Participants were randomized into 3 groups: whole breast radiotherapy at the standard dose of 40 Gy (n = 675; the control group), 40 Gy to the tumor bed and 36 Gy to the rest of the breast (n = 674), and 40 Gy to the tumor bed only (n = 669); the latter 2 groups were test regimens of focused radiotherapy to the tumor bed and lower dose (test 1) or no dose (test 2) to the rest of the breast.
The patients received intensity modulated radiotherapy (IMRT), a technique that delivers an even dose of radiation, thus minimizing hotspots of unwanted high doses and reducing the cosmetic problems that can occur after breast radiotherapy. This form of IMRT is simple, quick, and inexpensive, and it can be carried out with all standard radiotherapy equipment.
The researchers will continue collecting follow-up data for at least 10 years because cancer recurrence can occur more than 5 years after treatment is completed.
“The radiotherapy beams have a glancing orientation that covers the breast but limits the dose to the lung and also the heart in left-sided breast cancers. There is, therefore, no concern about a higher volume of low-dose radiation to normal tissue, which is sometimes a worry in more complex types of IMRT,” Coles explained.
“We hope that the evidence of benefit we have shown in this trial will bring about a change in practice worldwide, and enable very many more women with early breast cancer to undergo this treatment. At a time when breast cancer mortality rates are falling and more women are surviving their cancer, we believe it is particularly important to keep any treatment toxicity to the absolute minimum,” she concluded.
1. Coles C, Agrawal R, Ah-See ML, et al. Partial breast radiotherapy for women with early breast cancer: first results of local recurrence data for IMPORT LOW (CRUK/06/003). Plenary session presented at: 10th European Breast Cancer Conference; March 9-11, 2016; Amsterdam, The Netherlands. Abstract 4LBA.