Do you know that women with early-stage breast cancer don’t always have to undergo chemotherapy? A recent multinational study by Portugal and American scientists has found that a genetic test, called 70-gene signature test, can predict whether breast cancer patients need chemotherapy or not. In fact, using this test, as many as 46% of women with high clinical risk of breast cancer recurrence can skip chemo and still continue to live.
The study, carried out at 112 institutions in 9 European countries, was approved by the European Union (EU). The lead researcher, Dr Fatima Cardoso, MD, observed subjects from 2007 through 2011 and found the gene test to be highly effective in predicting the clinical outcome in women with high risk of metastasis and recurrence.
“Given these findings, approximately 46% of women with breast cancer who are at high clinical risk might not require chemotherapy,” said Dr Cardoso, Director of the Breast Unit of the Champalimaud Clinical Center in Lisbon, Portugal.
Breast cancer claims thousands of lives every year. In 2015, more than 230,000 US women were diagnosed with breast cancer, out of whom more than 40,000 women died. Breast cancer is a killer; it stands right behind lung cancer, the number 1 cancer killer in the world.
Early stage or Stage I breast cancer is categorized with tumors which are relatively small or have not spread to the lymph nodes. Surgeries like breast-conserving surgery (BCS), lumpectomy or partial mastectomy to remove the tumors are the immediate mode of action for early stage breast cancer. At times breast reconstruction surgery is also recommended.
After surgery there still remains a risk of metastasis — spread of cancerous cells from one part of the body to another. Breast cancer can spread from the lymphatic system since it can enter lymph vessels and grow in the lymph nodes, or even in other organs of the body.
The 70-gene signature test, also known as the MammaPrint test, can be used to predict the clinical utility of patients eligible for adjuvant chemotherapy. The genomic test developed by the company Agendia analyzes the activation potential of 70 genes related to breast cancer and then calculates a recurrence potential as either high risk or low risk. Through this test it can be determined if the activity of genes in early-stage breast cancer leads to a recurrence even 10 years later. The test is performed on a small sample of the cancerous cells derived from the breast cancer tumor.
A total of 6,693 women with early-stage breast cancer were enrolled in the study, out of which 1,550 patients (23.2%) had a high clinical risk and low genomic risk and thus were not given chemotherapy. After five years this groups was seen to have a survival rate of 94.7%.
No matter how small the tumor is, a majority of doctors recommend additional treatments after surgically removing stage I breast cancer tumors. According to the American Cancer Society (ACS), for women with breast cancer a tumor greater than 0.5 cm — ¼ inches in size — hormone therapy is recommended, but in women with a tumor smaller than 1 cm — ½ inch — chemotherapy is recommended.
Often women suffering from early stage breast cancer are subjected to treatment consisting of the adjuvant systemic therapy, which includes chemotherapy, endocrine therapy along with drugs which inhibit epidermal growth factor receptor 2 (HER2).
The decision to apply this treatment is based on factors like a patient’s age, menopausal status, HER2 status, tumor size along with lymph-node status. All these factors still fail to take the specific biologic characteristics of the tumor into account. Many experts believe a substantial number of patients are over-treated due to the absence of specific detection criteria. Over-treatment unnecessarily exposes these patients to toxicity.
Gene expression based studies had previously found breast cancer has four different molecular types. Genomic tests have also been developed to better determine if there is a chance of relapse. This large scale analysis may be a way to ensure for which specific patient chemotherapy can be beneficial while avoiding the unnecessary toxicity in others.
Chemotherapy And The Risk Of Metabolic Disorders
Another recent study highlighted how undergoing chemotherapy for breast cancer can increase the risk of developing metabolic disorders. Metabolic syndromes are described as critical conditions like heart disease, stroke and diabetes, which are a result of symptoms like high blood pressure, high fasting blood sugar, high triglyceride levels and low HDL cholesterol levels.
Women given chemotherapy for 12 to 18 weeks before or after undergoing surgery to remove breast cancer tumor have a significantly higher risk of developing a metabolic disorder. The study included 86 women with stage I to stage III breast cancer. After undergoing chemotherapy 72.5% of them were diagnosed with the metabolic syndrome and there was an increase in all of the symptoms.
According to Marisa Weiss, MD, founder and chief medical officer of Breastcancer.org: “It strongly suggests that chemotherapy — and all of the medicines that go with it, including steroids — increases the risk for metabolic syndrome and weight gain.”
The choice to undergo chemotherapy lies with the patient but better understanding of these mechanisms can enable the patients to better understand the risks and implications of their treatment choices.