Breast cancer treatments: Less invasive and disruptive

The war on breast cancer is advancing in more precise and targeted directions.

Doctors say, with new research and technological advances, they are increasingly able to offer women less invasive surgery and less radiation, with at least equivalent survival results, more convenience for the patient and fewer side effects.

The last couple of weeks have seen a few developments.

Researchers from the United States announced they had completed the most comprehensive genetic analysis of breast cancer undertaken so far. With better understanding of tumours, doctors would be able to offer more targeted and individualised treatment.

On Monday, at the annual conference of the European Society Of Medical Oncology in Vienna, investigators of a new drug called T-DM1 said it extended the lifespan of patients with a certain form of advanced breast cancer longer than standard treatment could. This has been just published online in the New England Journal Of Medicine. 

Breast cancer is the most common cancer among women here. Every year, about 1,500 new cases are diagnosed and about 400 people die from it.

With better treatment being developed for breast cancer, less can be more, said Dr Toh Han Chong, head of medical oncology at the National Cancer Centre, Singapore (NCCS).

In the last 10 years, treatment has evolved from being brutal to being gentler, easier and more sensitive, he added.

Survival rates are encouraging. The national five-year survival rates for breast cancer from 2006 to 2010 are 96 per cent for stage one cancer, 88per cent for stage two, 68 per cent for stage three and 25 per cent for stage four.

An example of a patient who has benefited from the new approach is Ms S, 58, who was diagnosed with early-stage cancer that had not spread to the lymph nodes. She had the tumour removed in an operation that conserved her breast, followed by targeted radiotherapy at the same sitting.

The entire process took only 21/2 hours and spared her from six weeks of conventional radiotherapy, which usually follows a month or so after surgery.

As her disease had been found early, she also avoided chemotherapy and was instead given the anti-hormone treatment her tumour type is known to respond well to.

Chemotherapy generally comes with more side effects, such as hair loss, nausea, mouth ulcers and loss of appetite.

TARGETED DRUGS

These side effects are reduced in the new drug, T-DM1, a two-in-one "Trojan Horse" made by Swiss drug company Roche.

This intravenous drug consists of a chemotherapy drug (DM1) linked to an antibody, trastuzumab, which latches onto a specific group of breast cancer cells that produce the protein HER-2.

About 25 to 30 per cent of all breast cancer patients have breast cancer that expresses HER-2.

Results from a major trial showed that T-DM1 prolonged the lives of patients with advanced HER-2-positive breast cancer by 30.9 months compared with 25.1 months on standard therapy. This is when a chemotherapy drug and an agent that targets HER-2 are given separately.

T-DM1 is delivered directly to the cancer cells without touching normal healthy cells, resulting in fewer of the side effects normally seen if just the chemotherapy drug is used, said Dr Raymond Ng, senior consultant medical oncologist at NCCS.

There were 991 patients who took part in the trial, including 12 patients from Singapore.

While waiting for the green light from the Health Sciences Authority here, T-DM1 is currently available to patients whom doctors think could benefit from the drug.

OVERCOMING RESISTANCE

Another smart drug is everolimus, a synthetically derived pill from bacteria found in the soil on Easter Island in the Pacific Ocean.

It enables the body to overcome resistance to therapy used against cancer that is sensitive to the female sex hormones oestrogen and/or progesterone, which make up more than 70 per cent of breast cancer cases.

"This is an important development allowing patients to potentially live longer by persisting with oestrogen-blocking drugs," said Dr Toh.

Hormonal therapy uses aromatase inhibitors (anti-oestrogen drugs) to stop the production of oestrogen in post-menopausal women.

These drugs cannot stop the ovaries from making oestrogen, so they work only in post-menopausal women.

They work by blocking the enzyme aromatase, which turns the hormone androgen into small amounts of oestrogen in the body.

This means that less oestrogen is available to stimulate the growth of hormone-receptor-positive breast cancer cells, thereby starving the breast cancer cells of the "growth nutrients" they crave, namely oestrogen and/or progesterone.

Anti-oestrogen tablets can control advanced disease while preserving the overall good quality of life, said Dr Toh.

But like all anti-cancer drugs, breast cancer cells can become resistant to anti-oestrogen drugs too.

Everolimus has the ability to reverse the resistance.

Studies have shown that if everolimus is combined with anti-oestrogen drugs, women with advanced, hormone-sensitive breast cancer can live with the disease for 10.6 months without it getting worse, compared with 4.1 months for those given just anti-oestrogen drugs.

This was published in February in the New England Journal Of Medicine.

"Just as you thought your weapon isn't working, everolimus is like an app that can potentially make it effective again," said Dr Toh.

SHORTER THERAPY SESSIONS

Breast cancer patients in the early stages of the disease who opt to keep their breasts, like Ms S, may qualify for a new treatment that cuts six weeks of radiotherapy to a single session of up to 40minutes.

The intra-operative radiotherapy (IORT) targets the tumour site after the tumour has been removed. Conventional radiotherapy is applied to the whole breast.

The landmark study shows that survival outcomes are the same for both with fewer side effects for IORT.

But cancer centres are treading cautiously, as IORT lacks long-term follow-up data of 10 to 15 years.

The NCCS, which currently has the only IORT machine here, has treated seven patients to date.

Dr Keith Lim, a consultant at the department of radiation oncology at the National University Cancer Institute, Singapore (NCIS) said doctors are divided over whether to adopt this new radiation schedule.

At NCIS, patients with early-stage tumours or pre-invasive cancer which has not spread to the adjacent lymph nodes are offered radiation delivered directly to the site of the tumour. This is done through radiation sources temporarily inserted into the breast twice a day for five days, said Dr Lim. This is different from IORT.

NCIS also offers hypo-fractionated radiotherapy for patients who have early-stage cancer, who are not keen to have radiation sources implanted.

This involves fewer sessions with higher doses of radiation given each time, but less total radiation.

Treatment is given over 21 sessions compared to the usual 30 sessions.

"Patients tolerate it well with comparable tumour control to those treated with 30 sessions," said DrLim.

INDIVIDUALISED TREATMENT

In what could bring the understanding of breast cancer one step closer to the final piece of the puzzle, the just-published paper in the journal, Nature, gives a highly detailed road map of the genetics of breast cancer.

Researchers, working under the umbrella of the Cancer Genomic Atlas network in the US, were able to identify six distinct sub-types of breast cancer.

In future, a woman with breast cancer could be recommended treatment known to be most effective against the particular sub-type of cancer she has.

Individualised treatment, as this is known, is a crucial goal of cancer treatment.

"This is one small strategic step for breast cancer treatment, but one giant leap towards curing breast cancer eventually," said Dr Toh.

This story was first published on October 4, 2012 on StraitsTimes.com.