Which is a better screening tool to detect breast cancer? KK Women's and Children's Hospital (KKH) Breast Imaging Unit shares details of the two screening tests.
Breast cancer is on the rise in Singapore like it is in the rest of the world. Every year, as many as 1,856 women, or about five women every day, are diagnosed with breast cancer in Singapore, making it the most common cancer among women here, according to the Singapore Cancer Register Interim Annual Report "Trends in Cancer Incidence in Singapore" 2010-2014.
To catch the cancer early, women aged 50 and above should go for a breast screening once every two years, and those between the ages of 40 and 49 should consider an annual screening.
Mammogram and ultrasound are commonly used to detect breast cancer. However, the mammogram is the primary screening tool for women who display no symptoms of the disease.
As an ultrasound is less painful than a mammogram, many women ask: Could I have an ultrasound instead of a mammogram to screen for breast cancer?
Dr Teo Sze Yiun, Senior Consultant and Head of the Breast Imaging Unit,
Department of Diagnostic and Interventional Imaging,
KK Women’s and Children’s Hospital (KKH), a member of the
SingHealth group, the answer is “No”. She explains, “A breast ultrasound should not be compared to a mammogram as these are two different imaging modalities with different functions. An ultrasound does not replace a mammogram or vice versa.”
A breast mammogram has been shown in multiple studies to be the only screening tool to decrease the number of deaths from breast cancer.
What is a mammogram?
A mammogram, a screening tool that has been around since the 1960s, uses low-dose x-rays to examine the breasts. Its aim is to detect early breast cancer when the chance of a cure is the highest.
The mammogram works by compressing the breasts for a few seconds so that two standard images – one vertical and one horizontal – can be taken of each breast. The breast compression is necessary to:
- Immobilise the breast
- Flatten and spread the tissue so that small abnormalities are not obscured
- Give the clearest image
“All these factors lead to a good quality mammogram which is essential for an accurate diagnosis,” says Dr Teo.
Is the radiation from a mammogram harmful?
“The benefit of early breast cancer detection far outweighs the small amount of radiation,” explains Dr Teo. “The dose of radiation is very small and has minimal scatter to other parts of the body.”
The images from the mammogram are separately analysed by two radiologists – this double reading has been found to increase the cancer detection rate. If the findings are uncertain, a woman may be called for further tests which include extra mammographic views and a breast ultrasound.
“About 5-10 per cent of women are asked to return for further tests. Typically, 90 per cent of these further tests indicate normal or benign (not suspicious) results,” says Dr Teo.
Read about the benefits of mammography and ultrasound of the breast in the next page.