Breast Cancer Management: A Medical Oncology Guide

The medical oncology management of breast cancer starts from the tumour's biology, not from the operating theatre. Every invasive breast cancer is classified by its receptors (oestrogen, progesterone and HER2) and by its stage, and that combination decides whether treatment begins with surgery, chemotherapy, hormone therapy, anti-HER2 therapy or immunotherapy. Early-stage disease treated this way is curable in the large majority of cases.

That was the central argument of Dr. Sahil Bambroo, Senior Consultant, Medical Oncology, BLK-Max Super Speciality Hospital, New Delhi, India, when he conducted this Jivo Masterclass for international doctors in March 2025. He chose not to dwell on textbook basics, which most doctors already know, and focused instead on the finer points and the misconceptions that persist even among doctors who treat breast cancer.

This guide follows his reasoning from classification to treatment choice. The front end of the pathway, from the first symptom to a confirmed tissue diagnosis, has its own article on breast cancer warning signs, self-examination and biopsy. The issues that dominate care for younger patients and long-term survivors (genetic risk, fertility, early menopause and bone health) are covered in breast cancer in young women: fertility and survivorship.

Breast cancer statistics: GLOBOCAN 2022 figures

Breast cancer mainly affects women, and it can rarely affect men. Dr. Bambroo framed its burden with GLOBOCAN 2022 figures, the global cancer statistics published by the International Agency for Research on Cancer:

• Breast cancer is the second most common cancer worldwide across both sexes, accounting for 11.5 per cent of all cancers; lung cancer is the most common.
• Among women it is the most common cancer, accounting for 23.8 per cent of cancers in women worldwide.
• By absolute numbers, most cases are reported from Asia, followed by Europe and North America. Africa accounts for 8.6 per cent of all breast cancer cases reported worldwide.

He added a point that puts the disease in perspective: across both sexes, lung cancer, not breast cancer, causes the most cancer deaths worldwide.

How breast cancer develops and spreads

Patients in the outpatient clinic often ask how and why their cancer began. Dr. Bambroo explains it as a progression. A single abnormal cell in the milk ducts or milk glands (lobules) grows and becomes atypical. While the abnormal cells remain inside the duct or lobule, the condition is non-invasive. Invasion begins when the cells breach the wall of the duct and spread into the surrounding tissue. Once cancer cells break through and reach the blood vessels or lymphatics, they can travel to other parts of the body, and the disease becomes metastatic.

This sequence is the logic behind the classification that follows, and behind the urgency of early diagnosis: each step outward worsens the prognosis.

Types of breast cancer: non-invasive, invasive and rare forms

Breast cancer is first classified as non-invasive or invasive, then by subtype and stage.

Non-invasive breast cancers are limited, early stages or precancerous conditions rather than frank cancers:

• Ductal carcinoma in situ (DCIS): abnormal cells in the breast ducts that have not spread beyond the ducts.
• Lobular carcinoma in situ (LCIS): abnormal cells in the milk glands that have not spread beyond the glands.

Invasive breast cancers are definite cancers:

• Invasive ductal carcinoma (IDC), which starts in the cells lining the milk ducts. It accounts for about 80 per cent of cases. Pathology reports often call it infiltrating ductal carcinoma.
• Invasive lobular carcinoma (ILC), which starts in the milk glands.
• Inflammatory breast cancer, in which cancer cells block the lymph vessels in the skin, so the breast looks inflamed. It is easily mistaken for infection, a trap described in the breast cancer warning signs article.

Rarer types include angiosarcoma, phyllodes tumour and Paget's disease of the breast.

Breast cancer receptor subtypes: ER, PR, HER2 and triple negative

Subtyping is what turned breast cancer into a disease treated by biology. Three receptors are tested on the biopsy by immunohistochemistry (IHC), a laboratory stain that shows whether a protein is present on the cancer cells: the oestrogen receptor (ER), the progesterone receptor (PR) and HER2 (human epidermal growth factor receptor 2). The results place an invasive cancer into one of four groups:

Dr. Bambroo noted that decision-making by cancer subtype has come in over the past few years. Based on these permutations and combinations, the oncologist decides what the primary treatment will be.

Breast cancer stages and survival

Like other cancers, breast cancer is staged from I to IV. The stage depends on the size of the tumour, the number of lymph nodes involved, and how far the cancer has spread locally and to other parts of the body. Stage matters because it shapes both treatment and survival. In the figures Dr. Bambroo presented, survival is around 100 per cent for stage I disease and falls to as low as 20 per cent for stage IV. Survival has improved with better techniques and medicines, but knowing the exact stage remains essential in every case.

Stage III is not a reason for despair: Dr. Bambroo stressed that even in stage III disease, surgery and the full range of treatment can be offered. The tests used to establish the stage are set out in the companion article on warning signs, diagnosis and biopsy.

Medical oncology management of breast cancer by subtype

In medical oncology, the receptor subtype sets the backbone of breast cancer treatment. Dr. Bambroo's treatment logic follows directly from the subtype table:

1. Hormone receptor positive, HER2 negative. Growth is driven by hormones. Surgery and chemotherapy are offered where needed, but hormone treatment is the priority.
2. Hormone receptor positive, HER2 positive. Both hormone therapy and anti-HER2 treatment are given, often combined with chemotherapy.
3. ER negative, HER2 positive. Anti-HER2 therapies are the core of treatment. These are antibodies that act against the HER2 receptor and help control the disease.
4. Triple negative. Neither HER2 nor hormones drive this cancer. Chemotherapy combined with immunotherapy can be given before surgery to reduce the extent of the disease, and surgery follows if the cancer is early. In metastatic triple-negative disease, surgery is out of the question.

He emphasised that a set method is followed in choosing therapy by subtype, because it matters both for downstaging the disease and for giving each patient the best possible outcome. For drug cost estimates, see the Jivo Healthcare pages on chemotherapy and immunotherapy.

Surgery is one step in breast cancer treatment, not always the first

Breast cancer treatment is multifaceted at any age. A central misconception Dr. Bambroo addressed is that breast cancer treatment means surgery. Treatment combines local therapies (surgery and radiation), endocrine (hormone) therapy, chemotherapy and, where genetic evaluation finds an inherited risk, treatment shaped by that result. It also has to address fertility, premature menopause, sexual health, body image, psychosocial functioning and rehabilitation after treatment.

Surgery is only one part of that journey, and in many cases it is not the first step. Often chemotherapy is given first to reduce the bulk of the disease, and the patient is then assessed for surgery. Dr. Bambroo sees the cost of the surgery-first message in practice. When the first doctor tells a patient that surgery is curative, many patients are operated on, become convinced the disease is gone, and conclude that no other treatment is needed. That belief is wrong. Patients counselled from the start that treatment is a long journey, with surgery as one part of it, are more willing to accept chemotherapy and hormonal treatment that may continue for years, depending on the extent of the disease.

Breast conservation or complete removal

For early breast cancer, Dr. Bambroo set out a simple decision rule:

• Tumour smaller than 2 cm, surgery feasible: breast-conserving surgery, in which the tumour is removed and the rest of the breast kept.
• Patient does not wish to conserve the breast, conservation is not feasible, or the disease is more spread: complete removal of the breast (mastectomy).
• Tumour larger than 2 cm, or potential for downstaging (shrinking the disease before surgery): induction therapy first, also called neoadjuvant therapy, meaning chemotherapy, or chemotherapy combined with immunotherapy in certain cases. The response then decides between complete and selective surgery.

The practical consequence is that many patients who would otherwise need a mastectomy can keep the breast, depending on how the tumour responds to initial therapy. The breast cancer surgery cost page covers both operations. Dr. Rajesh Kumar Jain sets out the surgical criteria for this choice in breast conservation surgery vs mastectomy.

He illustrated the reasoning with a clinical case: a 38-year-old woman scheduled for mastectomy and sentinel lymph node biopsy (removal of the first draining lymph nodes to check for spread), who was concerned about her appearance and asked about her options. The first requirement is complete staging. If scans, including a PET scan, show a single lesion in the breast, chemotherapy, combined with immunotherapy or anti-HER2 therapy where the subtype calls for it, can be given beforehand to shrink it, and surgery planned afterwards. Breast-conserving surgery is then possible, completed later with radiation therapy and with chemotherapy according to the subtype. If the disease is multicentric, involving different parts of the same breast, conserving the breast is probably not possible. These are the options Dr. Bambroo recommends explaining to patients in this situation.

Chemotherapy for breast cancer at any age

Age alone does not decide whether a patient with breast cancer can have chemotherapy. Many doctors assume that it does, but Dr. Bambroo's view is that age is a factor and not the deciding one. The extent of the disease, the biological characteristics of the tumour and the expected benefit matter more. At every age there are regimens that can be given safely, so patients' fear of chemotherapy should be put to rest rather than used as a reason to withhold treatment.

When chemotherapy can be omitted: gene expression tests

Chemotherapy can be omitted in a defined group of patients with early breast cancer, which avoids the opposite error of giving chemotherapy that will not help. For hormone receptor positive, HER2-negative early breast cancer with no or minimal lymph node involvement, gene expression profile tests such as Oncotype DX estimate the risk of the cancer recurring over 10 years. If the risk is low, chemotherapy can be omitted and reserved for patients at higher risk. Dr. Bambroo was clear that this applies only to a small subset of patients: early, node-negative or minimally node-positive, hormone-positive, HER2-negative disease. Dr. Rajesh Kumar Jain examines the same question in detail in can chemotherapy be avoided in early breast cancer.

Is breast cancer curable?

Definitive, curative treatment exists for early breast cancer. With protocols matched to the subtype, five-year survival is close to 100 per cent for stage I disease and above 90 per cent for stage II, because every subtype and every stage has a different protocol. Treatment is then adjusted for the patient's condition, other illnesses and what the patient can afford.

Metastatic breast cancer cannot be cured at present, but survival and quality of life have improved substantially compared with a few years ago. That improvement is the rationale for treating stage IV disease: quality of life matters, and survival matters. A protocol cannot be stated in one line. For every age, subtype and disease state, the treatment has to be optimised and the plan built around the individual patient, which is the essence of precision oncology.

How this masterclass fits with other Jivo Healthcare breast cancer guides

Several masterclasses on the site cover breast cancer from different angles, and each stands as its own guide:

• A surgical oncologist's view of diagnosis and operations: breast cancer diagnosis and surgery.
• A first-contact view for general practitioners: breast cancer diagnosis and management for GPs.
• Stage-by-stage treatment pathways: breast cancer treatment protocol by stage and subtype.

The questions doctors put to Dr. Bambroo at the end of the session, on where to take a biopsy, what causes breast cancer and whether a cure exists, are answered in the Live Discussion. More oncology masterclasses are listed on the oncology specialty page.