Over the past decade, Malaysia has seen a significant increase in breast cancer cases.
According to the National Cancer Registry Report 2012-2016, roughly 34 women out of 100,000 developed breast cancer in 2012-2016.
Almost half (47.9%) were only diagnosed at the more advanced stages of the disease.
Currently, breast cancer remains the most common cancer affecting women and is responsible for the second highest number of cancer-related deaths in the country.
Most breast cancer-related deaths can be attributed to advanced breast cancer.
Also known as secondary or metastatic breast cancer, it is defined as the spread of breast cancer cells to other parts of the body, such as the lymph nodes, bone, lungs, liver or brain.
While previously assumed to be a disease affecting elderly women, more recent statistics have shown that younger, pre-menopausal women are also susceptible to the condition.
In fact, advanced breast cancer in pre-menopausal women tends to be more aggressive with a higher risk of recurrence, leading to increased risk of death.
Consultant clinical oncologist Dr Mastura Md Yusof notes that: “Younger women with breast cancer also suffer from the added pressure of having to work fulltime and care for their children, while managing the disease.”
Advanced breast cancer is typically divided into different subtypes based on the presence of specific receptors, including hormone receptors (HR+ or HR-) and human epidermal growth factor receptors-2 (HER2+ or HER2-).
This subclassification is crucial in order for oncologists to select effective treatment regimens.
However, genetic testing of breast cancer tumours has revealed that approximately 40% of women with HR+/HER2- advanced breast cancer (the most common type) also have the PIK3CA mutation.
This mutation is linked to tumour growth, resistance to endocrine treatment and an overall poor prognosis.
Explains Dr Mastura: “In each type of cancer, gene mutations play a role in determining how rapidly or invasive a cancer may become.
“In the case of HR+/HER2- advanced breast cancer patients, the PIK3CA mutation found within the tumour can tell us whether this gene mutation may be contributing to the progression of the disease, giving rise to the question of whether we can target it with medicines to control it.”
Fortunately, a recent phase 3 clinical trial found that combination treatment with a new selective inhibitor of the PIK3CA molecule and traditional oestrogen-receptor blockers nearly doubled the survival duration of patients with HR+/HER2- advanced breast cancer, compared to using oestrogen-receptor blockers alone.
This biomarker-driven treatment is now available in Malaysia.
Dr Mastura notes that many advanced breast cancer patients suffer from recurring or advancing cancer after completing or while still on their hormone-based treatment, despite receiving optimal treatment.
Such patients are encouraged to get screened for the PIK3CA gene mutation, as they might benefit from the biomarker-driven treatment.
“In those found to be positive for PIK3CA, this treatment will help to inhibit cancer growth by acting together with standard oestrogen receptor-blockers that we use at present to better reduce cancer growth,” she says.
Novartis Oncology Division country medical director Dr Balraj Sethi says: “We have long suspected that combating the effects of the PIK3CA gene and its pathways were key to halting the progression of HR+/HER2- advanced breast cancer and improving the odds of survival.
“With the recurrent and progressive nature of advanced breast cancer, clinicians have long sought for answers on how best to tailor their treatment regimes.
“Now, we finally have an answer for patients with this particular genetic mutation.”