Benefit of Radiotherapy after Lumpectomy
by Amanda Remington, Information Resource Specialist
The Berkeley Institute for Advanced Cancer Therapy
Radiation therapy is often times the recommended treatment for early breast cancer once surgery is complete. Radiation is used to help eliminate cancer cells that may have been left behind after surgery. If not eradicated, such left over cancer cells can form new lumps referred to as "local recurrences." A number of different forms of radiation has been found useful depending on the patient's cancer, but a few facts stay the same. For one, recurrence prevention by radiotherapy is found be be substantial. Test groups from a number of studies were found to have a higher recurrence rate if they did not receive radiation. However, studies show that radiotherapy may not extend life by much.
In one study published in the Journal of National Cancer Institute entitled "Breast-Conserving Surgery With or Without Radiotherapy: Pooled-Analysis for Risks of Ipsilateral Breast Tumor Recurrence and Mortality," by Vincent Vihn-Hung et al., fifteen clinical trials were pooled together in order to have a larger base of patients from whom to draw conclusions. The pooled trials gave a grand total of 9422 patients that had participated in early breast cancer comparison trials.
In this pooled study, Vihn-Hung et al. compared two main groups of patients: one group received breast-conserving surgery but no radiation and the other group underwent the same type of surgery but then received radiotherapy afterwards. The results showed that the group who did not receive radiation had a significantly higher rate of recurrence (three times more recurrences) than the group who received radiation. There was a relapse rate of 1.4% - 5.7% in the groups that received no radiotherapy compared to 0.4% - 2.1% in the radiotherapy groups.
Based on the comparison, radiation provides an extremely high statistically-significant benefit in regards to recurrence. Interestingly, further examination of data in the same pooled study found that although patients in the radiation group were having less recurrences, their lives were not prolonged by much compared to the group that received no radiation.
In one of the pooled analyses, Vihn-Hung et al. found only an 8.6% survival benefit in an early breast cancer group that received radiation versus the group that did not. This low percentage dropped even further as the age of patients rose. How much survival benefit gained depended also on what form of surgery a patient received. For example, a woman with a one centimeter lump that is estrogen receptor-positive may only gain a 0.5% - 1.5% survival benefit. Many of the other subgroups of patients had even smaller benefits. Vihn-Hung et al. concluded that radiation does prevent recurrences but does not prolong life by much.
In an article published in the Lancet entitled "Effect of radiotherapy after breast-conserving surgery on 10-year recurrence and 15 year breast cancer death: meta-analysis of individual patient data for 10,801 women in 17 randomized trials", a similar comparison was made. Seventeen randomized trials with a total of 10,801 patients with early breast cancer were reviewed to see if patients benefited from radiotherapy in any significant way. Of the total, eight thousand three hundred thirty seven (8337) patients had access to their pathology reports depicting whether there was axillary lymph node spread present. Pathology reports are papers describing and detailing the diagnosis after examining cells under a microscope. For the women who had histology reports indicating a cancerous node, radiation was found to lower the ten year recurrence rate from 63.7% to 42.5% (absolute reduction 21.2%). In regards to their survival, radiation was found to bring the fifteen year risk of breast cancer death from 51.3% to 42.8% (absolute reduction 8.5%). For women with no cancerous nodes recurrence risk dropped from 31.0% to 15.6% (absolute reduction 15.4%). Radiation brought the mortality risk of node negative patients from 20.5% to 17.2% (absolute mortality reduction 3.3%). This proves that radiation does provide a long term benefit against recurrence. However, this study found that more women in the radiation group succumbed from other malignancies. Radiation has proven once again to be beneficial for patients afraid of recurrence, but there is limited survival benefit in all comparisons.
Patients must keep in mind that radiation comes with its own risks as discussed in the Lancet article. Radiation takes weeks to complete and can result in side effects that are very discomforting. Common occurrences are skin irritation, hardening of the breast, and discomfort when pressure is applied. Daily radiation sessions five days a week for at least one month can also be very time consuming to receive little to no survival benefit. Radiation's ability to prevent cancer cells from spreading is commendable, but the end goal is to provide a higher survival benefit. If preventing recurrence does not prolong survival then a patient might find themselves spending a large sum of time and money without gaining the results they seek. Knowing the benefits and drawbacks of every step of cancer treatment is important and the more a patient knows the easier it is to make an informed decision. Risk of radiation causing new cancer will be discussed in a subsequent article.