Breast Cancer Awareness Month: Single-dose radiotherapy as good as conventional one for most in early stage
For most women with early breast cancer, a single dose of targeted radiotherapy during surgery is just as effective as conventional radiotherapy which requires several visits to the hospital after surgery. Researchers found that the combination of targeted radiotherapy given immediately after surgery — otherwise known as targeted intraoperative radiotherapy — is associated with around an 80% chance of avoiding a full course of conventional radiotherapy, fewer side effects, and no difference in survival or likelihood of the cancer returning.
The findings, published in The BMJ, are based on 2,298 women with invasive ductal carcinoma (IDC), aged 45 years or older, who were eligible for breast conservation surgery (lumpectomy) at 32 centers in 10 countries in the US, the UK, Europe, Australia and Canada. The most common type of breast cancer, an estimated eight in 10 invasive breast cancers are invasive ductal carcinomas. Based on the results, the authors recommend that single-dose radiotherapy can replace the need for extra hospital visits, with benefits for patient safety and well-being.
Conventional radiotherapy involves repeat doses to the whole breast over several days after surgery. Results from an earlier report of single-dose targeted intraoperative radiotherapy were promising, but doctors have been waiting for longer-term results before adopting the procedure more widely. Accordingly, an international team of researchers from institutes in the US, the UK, Australia, Norway, Germany, Italy, Switzerland, Poland, Denmark and Canada, set out to compare the long term effects of targeted intraoperative radiotherapy (TARGIT-IORT) with conventional whole breast external beam radiotherapy (EBRT) for women with early breast cancer.
Between March 24, 2000, and June 25, 2012, 1,140 women were randomized to receive targeted intraoperative radiotherapy and 1,158 received external beam radiotherapy. TARGIT-IORT was given as a single dose immediately after surgery as part of the same operation and under the same anesthetic, while EBRT was given as a standard daily dose for 3-6 weeks after surgery. The long term results show that TARGIT-IORT was no worse than EBRT. After five years of monitoring, the local recurrence risk was 2.11% for TARGIT-IORT compared with 0.95% for EBRT. This difference of 1.16% is not considered clinically significant.
In the first five years after surgery, there were 13 additional local recurrences (24 out of 1,140 vs 11 out of 1,158) but 14 fewer deaths (42 out of 1,140 versus 56 out of 1,158) with TARGIT-IORT compared with EBRT. Over a longer follow-up period — average 8.6 years, maximum 18.9 years — there were no statistically significant differences in local recurrence-free survival (167 versus 147 events), mastectomy-free survival (170 as compared to 175 events), overall survival (110 versus 131 events) and breast cancer deaths (65 as compared to 57 events).
Breast cancer-specific mortality was similar for both arms, but far fewer deaths were reported from causes other than breast cancer in the TARGIT-IORT arm. The analysis reveals that deaths from other causes were significantly lower, 45 versus 74 events, with TARGIT-IORT compared with EBRT. The major risk factors for such deaths (age and body mass index) were well matched between the groups, the team explains. The researchers point to some study limitations, such as possible overdiagnosis of non-invasive local recurrence affecting the results, and not collecting all the background risk factors for deaths from non-breast cancer causes. However, strengths include the randomised design, a large sample size with a long duration and high level of complete follow up, suggesting that the results are reliable and robust, they add.
The researchers say that as such, for the large proportion of early breast cancer patients, risk-adapted immediate single-dose TARGIT-IORT during a lumpectomy is an effective alternative to EBRT, with comparable long-term efficacy for cancer control, and lower non-breast-cancer mortality.
“We believe that the long term data presented in this paper, together with many benefits for the patient, provide compelling evidence in favor of TARGIT-IORT as an effective alternative for this large group of patients with early breast cancer who are suitable for breast conservation. Single-dose TARGIT-IORT during lumpectomy should be accessible to healthcare providers and discussed with patients when surgery for breast cancer is being planned,” write authors. They conclude: “Ultimately the treatment patients receive should be their choice and they should be provided with the data in a format which is transparent, straightforward, and easily understood.”