A clinical trial comparing a shortened schedule of higher-dose radiation therapy to the standard timing and dosage found the treatments worked equally well at decreasing the risk for recurrence in the breast and preserving its appearance.
The study, published in The New England Journal of Medicine, was performed in women who had lumpectomies to remove invasive disease confined to the breast.
Background of Radiation Therapy
Previous studies have shown that whole-breast radiation given after lumpectomy decreases the chance of recurrence in the breast and also may improve overall survival in women with early-stage breast cancer. Yet up to one-third of women who have lumpectomies do not undergo radiation treatment.
Researchers suspect that some women skip radiation therapy because of costs and inconvenience. Standard radiation treatment is given once per day, every day, for five to seven weeks, a challenging regimen for those who live far away from their treatment facility, have financial problems or cannot take time off work.
Background of the Hypofractionation Study
To help more women access treatment, researchers began to study a shortened course of radiation in which a larger daily dose (hypofractionation) is given over a shorter period of time (accelerated therapy).
In this study, researchers compared a shorter course of radiation to standard radiation for its ability to:
- Reduce risk for local recurrence, a return of the cancer in the area where it started in the breast
- Maintain the appearance of the treated breast
Structure of the Study
Study participants had invasive breast cancers of 5 centimeters or less that had not traveled to the lymph nodes. All had lumpectomies that resulted in clear margins, when cancer cells are found away from the edges of breast tissue removed during surgery.
The 1,234 participants were randomly assigned by computer to receive one of two radiation treatments:
- The standard therapy of 25 fractions (treatments) of 200cGy per treatment, given for five days each week over five weeks
- The treatment under study of 16 fractions of 42.5 Gy each, given for five days each week over three weeks
Depending on the type of cancer, women also may have received chemotherapy, tamoxifen or both. After initial treatment, participants saw their doctors every six months for five years and then annually.
After an average of ten years of follow-up, 7.5 percent of women in the standard group had a local recurrence versus 7.4 percent of women in the study group. The findings held true regardless of the participant’s age, tumor size or estrogen-receptor status.
Hypofractionated radiation worked less well than standard radiation at reducing local recurrence in women with high grade tumors, cancers with very abnormal cells that reproduce quickly.
All women had breast changes over time resulting from radiation therapy, but the changes were similar in the groups: 71.3 percent of women in the standard group had a "good or excellent cosmetic outcome," compared to 69.8 percent in the study group.
Limitations to the Study
This study did not include participants with large breasts or with DCIS (ductal carcinoma in situ) or invasive disease present in the lymph nodes. Also, participants in both arms did not receive a "boost" of radiation at the end of treatment—a standard of care today—which could impact the look of the breast over time.
What This Study Means for You
Further research will help doctors learn about the effectiveness of hypofractionated radiation, but this study suggests is may be an appropriate choice if you have early-stage breast cancer and would not normally receive a lumpectomy-site "boost" (typically true for older women), have smaller breasts and you do not need chemotherapy as part of your treatment. Always talk with your doctor about the potential risks and benefits of treatment.
TJ Whelan et al, Long-Term Results of Hypofractionated Radiation Therapy for Breast Cancer. N Engl J Med 2010; 362: 513-20.