A critical component of the multidisciplinary management of invasive breast cancer.
In select patients improves local control, can spare patients from the morbidity of local recurrence, can improve survival, presumably by preventing seeding and reseeding of metastases from reservoirs of local and regional disease.
Patients who undergo lumpectomy and those with high risk doseaev post mastectomy with tumor greater than 5 cm and positive lymph nodes usually receive adjuvant radiation therapy.
Adjuvant radiotherapy for breast cancer often includes the axillary, and in high-risk patients comprehensive nodal it radiation of the supraclavicular and paraternal regions may be included.
Patients with node-positive disease who receive breast conserving therapy routinely receive adjuvant whole breast radiotherapy covering the lower and lateral axilla and often receive more comprehensive nodal therapy for the supraclavicular and superior internal mammary lymph nodes which improves disease free and metastases free survival.
In the NSABP B-06 randomized trial, the 20 year ipsilateral breast tumor recurrence rate was 14.3% after lumpectomy with whole breast radiation versus 39.2% after lumpectomy alone.
Randomized studies show mortality benefit from postmastectomy radiotherapy in patients with 1-3 positive axillary nodes, but this technique remains underused, particularly after breast reconstruction.
The Early Breast Cancer Trialists’ Collaborative Group meta-analysis suggested a modest benefit in overall survival with the addition of radiotherapy: 10,801 women in 17 trials of radiation or no radiation after lumpectomy, radiation reduced the 10 year risk of any recurrence in lymph node negative women from 31% to 15.6% and reduced the 15 year risk of death from breast cancer 20.5% to 17.2%.
In the above study not all subgroups attain the same benefit from radiotherapy.
Among women with low risk early breast cancer treated with radiotherapy to the breast tumor bed alone as compared with those patients receiving whole breast irradiation local recurrence rates were no higher (European Breast Cancer Conference 2016 IMPORT-LOW Trial).
In the above study partial breast radiotherapy had equivalent control of the cancer but less side effects of patients than whole breast radiation.
There is a substantial mismatch between patient and physician reports of toxicity during radiotherapy for breast cancer, according to an analysis of nearly 10,000 U.S. patients.
Physicians underrecognized four key symptoms – pain, pruritus, edema, and fatigue during radiotherapy
Factors independently associated with symptom underrecognition were younger age, Black or other non-White race, conventional fractionation, and being treated at an academic center.
The use of boost radiation has a small but statistically significant reduction in breast tumor recurrence risk of 4% at 20 years in all age groups for invasive breast cancer.
Hypo fractionated whole breast radiation reduces treatment duration to 3-4 weeks with similar efficacy and toxicity profiles as standard whole breast the radiation given for 5 to 7 weeks.
In DCIS patients treated with lumpectomy and whole breast radiation, with boost RT or no boost: a decrease in tumor recurrence was seen in the boost group at 15 years of 91.65 vs 88% in a pooled analysis.
Radiation therapy may be avoided older patients with low risk tumors: PRIME II study of breast conserving surgery with or without radiation in women age 65 years or older with early breast cancer receiving endocrine therapy- adjuvant radiation therapy was associated with a small but statistically significant reduction in local recurrence with no differences in rates of distant metastasis or overall survival.
The cancer and leukemia Group B 9343 trial of women 70 years or older with stage one ER positive breast cancer received adjuvant therapy after lumpectomy and radiation or no radiation: local recurrence rate of 10 year follow up with slightly lower in the radiation therapy group, but breast cancer specific and overall survival rates are comparable.
The maximal toxicity reported by 8,711 patients treated: breast pain, itching, stinging/burning, swelling, or hurting of the treated breast, and fatigue within 7 days of completing whole-breast radiotherapy.
Moderate or severe breast pain was reported by 3,233 (37.1%): 1,282 (28.9%) of those receiving hypofractionation and 1,951 (45.7%) of those receiving conventional fractionation.
Complaint of at least one breast symptom was reported by 4,424 (50.8%): 1,833 (41.3%) after hypofractionation and 2,591 (60.7%) after conventional fractionation.
Fatigue is reported by 2,008 (23.1%): 843 (19.0%) after hypofractionation and 1,165 (27.3%) after conventional fractionation.
Hypofractionated radiotherapy and breast pain associated with younger age, higher body mass index, Black race, smoking, larger breast volume, lack of chemotherapy receipt, receipt of boost treatment, and treatment at a nonteaching center predicted breast pain.
Breast pain among patients receiving conventionally fractionated radiotherapy: younger age,higher BMI, Black race, diabetes,smoking status and larger breast volume.
Some patients treated with anthracuclines, and targeted therapies have an increased risk of cardiovascular disease with radiotherapy.
Patients with pre-existing cardiovascular risk factors of hypertension, obesity, diabetes, and increased coronary artery calcification have higher risk of treatment induced cardiotoxic effects.
Women with large breast size have increased risk of radiation related toxic effects.
Treatment in the prone position is less toxic than in the supine position in women with large breast size receiving adjuvant breast radiation: decreases excess lung exposure, improves dose homogeneity and decreases the risk of moist desquamation.