From the Guidelines
Radiation therapy is indicated for most breast cancer patients after breast-conserving surgery (lumpectomy) to eliminate any remaining cancer cells and reduce recurrence risk. This recommendation is based on the results of a meta-analysis by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) showing reduction in 10-year risk of recurrence in those who received whole breast irradiation versus those who did not (19% vs 35%; relative risk [RR], 0.52; 95% CI, 0.48–0.56) 1.
Indications for Radiation Therapy
- After lumpectomy, whole breast irradiation is strongly recommended with or without boost to tumor bed for node-positive disease (category 1 for those with positive nodes; category 2A for those with negative axillary nodes) 1.
- Postmastectomy irradiation is recommended for patients with tumors larger than 5 cm, positive lymph nodes, or positive surgical margins.
- Regional lymph node irradiation is recommended in patients treated with lumpectomy in situations analogous to those recommended for patients treated with post-mastectomy irradiation.
- Radiation therapy to the infraclavicular region and supraclavicular area is recommended for patients with 4 or more positive lymph nodes (category 2A), and should be strongly considered in those with 1 to 3 positive lymph nodes (category 2B) 1.
Treatment Planning and Dosage
- Whole-breast radiation typically involves 15-20 treatments over 3-4 weeks, while some patients may qualify for accelerated partial breast irradiation delivered over just 1-2 weeks.
- The recommended radiation dose for whole-breast radiation is 45 to 50 Gy in fractions of 1.8 to 2.0 Gy, or 42.5 Gy in fractions of 2.55 Gy to the ipsilateral chest wall, mastectomy scar, and drain sites 1.
- An additional boost dose of 10 to 16 Gy radiation in 2-Gy single doses is recommended for patients who are at high risk for disease recurrence (eg, age <50 years with high-grade tumors) 1.
Side Effects and Considerations
- Common side effects include skin irritation, fatigue, and breast swelling, which are usually temporary.
- Treatment planning involves CT simulation and careful dosimetry to maximize tumor coverage while minimizing exposure to the heart, lungs, and other healthy tissues.
- Some patients may avoid radiation if they are elderly with small, hormone-positive tumors taking endocrine therapy, as their recurrence risk is already low.
From the Research
Indications for Radiotherapy in Breast Cancer
The indications for radiotherapy in breast cancer are as follows:
- After conservative surgery for an infiltrating carcinoma, radiotherapy must be systematically performed, regardless of the characteristics of the disease, because it decreases the rate of local recurrence and specific mortality 2
- A boost dose over the tumour bed is required if the patient is younger than 50 years-old 2
- Adjuvant radiotherapy must be systematically performed after lumpectomy for ductal carcinoma in situ 2
- After mastectomy, chest wall irradiation is required for pT3-T4 tumours and if there is an axillary nodal involvement, whatever the number of involved lymph nodes 2
- After neoadjuvant chemotherapy and mastectomy, in case of pN0 disease, chest wall irradiation is recommended if there is a clinically or radiologically T3-T4 or node positive disease before chemotherapy 2
Patient Selection for Radiotherapy
The decision to use radiotherapy should be based on individual prognostic parameters and technical possibilities, considering the risk and benefit of radiotherapy 3
- Women with early stage invasive breast cancer (stage I and II) who have undergone breast conservation surgery should be offered postoperative breast irradiation 4
- The optimal fractionation schedule for breast irradiation has not been established, and the role of boost irradiation is unclear 4
- Radiation therapy given after lumpectomy reduces the frequency of ipsilateral breast recurrences even in women with small breast cancer with several favourable clinical and biological features 5
Radiotherapy Techniques
- Hypofractionation regimens (42.5Gy in 16 fractions, or 41,6Gy en 13 or 40Gy en 15) are equivalent to conventional irradiation and must prescribe after tumorectomy in selected patients 2
- Delineation of the breast, the chest wall and the nodal areas are based on clinical and radiological evaluations 2
- 3D-conformal irradiation is the recommended technique, intensity-modulated radiotherapy must be proposed only in specific clinical situations 2
- Respiratory gating could be useful to decrease the cardiac dose 2