The advances of radiotherapy in early breast cancer treatment

Dr Yael Mark explains the importance of radiotherapy, and the progress it has made in early breast cancer treatment.

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HOW COMMON IS BREAST CANCER?

Worldwide breast cancer is the most commonly diagnosed cancer in women and a leading cause of cancer related death in females. In South Africa 1 in  28 women will be diagnosed with   breast cancer in her lifetime¹.

Screening mammography is responsible for the biggest contribution to early breast cancer detection and  thus a reduction in mortality, related to breast cancer.

TREATMENT OVERVIEW FOR EARLY STAGE BREAST CANCER

The treatment of breast cancer involves a multi-disciplinary team of doctors, including a breast surgeon, radiation and medical oncologists. Managing a patient with a team approach has been shown to reduce mortality and improve treatment outcomes².

Early stage breast cancer includes patients with small tumours and no or minimal disease spread to the axillary nodes (underarm glands). These patients are generally treated with a combination of surgery to the breast and axilla, with or without radiotherapy. They may be offered systemic therapy, depending on tumour characteristics, such as size, aggression, grade and hormone  receptor status. 

BREAST CONSERVATION – WHERE DOES RADIOTHERAPY FIT IN?

Traditionally, women with breast cancer were treated with a mastectomy, which involved loss of the whole breast. Questions arose as to the possibility of breast-conserving surgery, where the tumour is removed with a small amount of normal tissue, without sacrificing the entire breast. 

The concern with this approach is the possibility of leaving behind cancer cells in the tumour bed and the vicinity of the removed cancer. These cells are referred to as microscopic residual disease. They can’t be seen with the naked eye but they have the potential   to result in regrowth of the cancer. To combat this, any patient treated with breast-conserving surgery requires radiotherapy post-operatively, to sterilise the breast of any remnant cancer cells³.

Essential criteria for acceptability of the breast-conserving approach are the ability to achieve equivalent oncologic outcomes to mastectomy with regards to local control as well as patient survival. 

High level data has proven the equivalence of the two treatment approaches. However, the safety of breast-conserving therapy is dependent upon the patient receiving post-operative breast radiotherapy⁴. 

Therefore, patients who aren’t candidates for radiotherapy can’t have breast-conserving surgery. Examples    of patients who aren’t suited to this approach include: patients who have previously received radiotherapy to the breast; patients who refuse radiotherapy; and patients with multicentric breast disease (tumours in multiple areas  within the breast).

HOW DOES RADIOTHERAPY WORK?

Radiotherapy to the breast is planned after performing a planning CT scan, to optimise the accuracy of radiotherapy delivery. It involves daily treatment, five times a week from Monday to Friday, on a radiotherapy machine, called a linear accelerator. 

Treatment is painless and each session takes approximately 15 minutes. Breast radiotherapy is generally well-tolerated with most patients being able to continue their normal daily routines. The most common side effects are mild fatigue and some skin changes at the treated area, including sensitivity, redness and itching, similar to a sunburn. The overall number of radiotherapy sessions needed to effectively treat breast cancer has also undergone changes in the modern era.

Traditionally, breast cancer patients required five to six weeks of treatment with between 25 to 33 sessions of radiotherapy. However, new evidence has emerged to support shorter duration radiotherapy treatment in certain well-selected groups of patients. These patients were women aged 50 years or older, with early stage, node negative and hormone receptor positive breast cancers.

THE EVIDENCE FOR SHORT-COURSE RADIOTHERAPY

The START A and B trials were conducted, in the UK, and were published in the Lancet Journal of Oncology, in 2013. A similar trial was conducted in Canada⁵. These trials all showed that treatment with radiotherapy for three weeks, or 15-16 treatments, was equivalent to the longer treatment course with regards to disease control, side effects and cosmetic outcomes^6,7. This type of radiotherapy is termed: hypo-fractionated breast radiotherapy. It involves treating with a higher daily dose but for a shorter overall treatment duration.

The latest guidelines from the American Society of Radiation Oncology support the use of short-course breast radiotherapy in a wider population of patients then ever before, including women of younger and older ages and also tumours of all grades⁸. 

PROGNOSIS AND OUTCOMES

Overall, the approach to treating breast cancer has become more conservative and minimalist over time with a focus on reducing the length, cost and invasiveness of treatment, without compromising the cosmetic and oncologic outcomes. For the majority   of patients with early breast cancer the prognosis is excellent and most women will remain in remission for the rest of their lives.

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MEET OUR EXPERT – Dr Yael Mark

Dr Yael Mark is a radiation oncologist and practices at the Sandton Oncology Centre and West Rand Oncology Centre. She has a special interest in breast, head and neck- and prostate cancers.

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