The many lives of breast cancer: understanding rare subtypes Premium

Explore the diverse subtypes of breast cancer, their unique characteristics, and the importance of early detection and treatment.

Conversations about breast cancer usually bring up a single picture in one’s mind: a woman feels a lump, gets it tested, is told she has breast cancer, and then follows a pathway of surgery, chemotherapy, radiation and hormone tablets. That picture is almost always based on the commonest form of the disease – what the World Health Organization now calls “invasive carcinoma of no special type” (NST), formerly known as invasive ductal carcinoma. Around 70–80% of invasive breast cancers fall into this group.

But breast cancer is not one disease. Under the microscope, it is a family of diseases that all happen to arise in the breast. Some are aggressive, some are surprisingly gentle, some have not yet turned into true cancer, and some occur in groups we rarely talk about, such as men. The subtype of breast cancer in the pathology report can change the likely behaviour of the disease and the kind of treatment it needs.

In India, where breast cancer has become the most-commonly diagnosed cancer among women in many urban registries, these rare forms are not a side-show: they are part of the everyday reality of oncology.

Once a lump is detected on examination or imaging, the next crucial step is tissue diagnosis. In modern practice, this is usually done on small samples taken with a core needle biopsy. The pathologist then studies thin slices of this tissue under the microscope and performs special stains to look for hormone receptors and other markers.

From this process comes the pathological diagnosis. It tells us: whether there is cancer at all, where it seems to have started (ducts vs lobules), what pattern the cells form, and whether they express oestrogen, progesterone or HER2 receptors.

Two women may both hear the words “you have breast cancer” but have very different diseases under the microscope. At this stage, communication between the radiologist, pathologist and surgeon is indispensable. The image, the biopsy and the clinical examination must all make sense together, especially when the pattern is unusual. This is why multidisciplinary breast units – where these specialists work together – are important to manage rare types safely.