Breast Radiotherapy

All patients with invasive breast cancer who have had breast-conserving surgery routinely receive post-operative whole-breast radiotherapy. The Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) systematic overview confirms that such treatment yields a 75% reduction in the risk of local tumour recurrence. The overview also indicates that the prevention of four local tumour recurrences will prevent one death from breast cancer at 10 years. Whole-breast radiotherapy (WBRT) has historically been delivered over 5 weeks, treating at 2 Gray (Gy) per fraction, equating to a total dose of 50 Gy delivered to the breast. Among those women where mastectomy is more appropriate, because the tumour is multifocal, too large for breast conservation or for personal reasons, some patients will be selected for radiotherapy to reduce the risk of chest wall recurrence. Typically, radiotherapy is recommended after mastectomy for women with four or more axillary lymph glands, tumours greater than 5 cm (T3), or positive deep margins.

Whilst the benefits of radiotherapy are recognised, with the increasing incidence of breast cancer and falling mortality, the non-breast cancer deaths are increasingly relevant to the growing population of long-term breast cancer survivors. In addition, the advances in medical imaging and radiotherapy planning techniques, and improvements in radiotherapy treatment machines, have led to a real opportunity to optimise breast dosimetry for the patient. In this review we will discuss current and future strategies for optimising breast radiotherapy treatment. These include:

Novel fractionation

Hypofractionation entails the delivery of larger doses per fraction to yield a biological effect equivalent to standard 2 Gy radiotherapy schedules. The UK Standardisation of Breast Radiotherapy Trial (START) compared conventional treatment of 50 Gy in 25 daily fractions over 5 weeks with the delivery of 15 fractions over 3 weeks. The local recurrence rates were equivalent at 5 years. Similar data has been reported in a Canadian study comparing 16 fractions with 25 daily fractions. As a consequence NICE recently advised that hypofractionation should be adopted as a standard regimen within the UK.

With the adoption of hypofractionation as a standard of care in the UK, there are key improvements in efficiency of treatment in terms of treatment delivery. In order to test the hypothesis that hypofractionation may offer a radiobiological advantage, the Faster Radiotherapy for Breast Cancer Patients (FAST) study compared larger doses (5.7-6 Gy) of radiotherapy given once weekly for 5 weeks with conventional 2-Gy daily treatment in early breast cancer. This showed non-inferiority with respect to local control and cosmetic outcome at 28 months median follow-up and potentially has clear gains in terms of patient convenience and radiotherapy resource utilisation. The Fast Forward trial is currently in set-up to further evaluate this compared to the current UK standard of 40 Gy in 15 daily fractions over 3 weeks.

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