Changing Paradigm and Making Breast Cancer Treatments More Effective and Less Invasive

For many years, breast cancer was treated as a single entity, with the standard approach for early- stage disease being surgery followed by chemotherapy and radiotherapy. However, advancements in molecular biology have transformed this paradigm. We can now categorize breast cancer into four main groups, allowing for more personalized treatment strategies. This classification, based on receptor status (ER/PR/HER2) and mitotic grades, enables surgeons and oncologists to tailor therapies to individual patients, minimizing unnecessary side effects and improving overall outcomes.

The 4 main groups of breast cancer are:

Luminal A-tend to be ER/PR+ve, HER2–ve, low grade tumours. About 30-70% of breast cancers are Luminal A. Tumours respond to hormonal therapy and has the best prognosis among the 4 sub-types.
For early breast cancer, Luminal B-tend to be ER/PR+ve, may be HER2+ve or -ve, high grade tumours. Women tend to be younger at diagnosis. Around 10-20% of breast cancers are Luminal B type.
Triple negative tumours are tumours with no receptors, these tumours tend to be aggressive, and spread to vital organs early. Around 15-20% of breast cancers are triple negative. Although it is associated with poor prognosis, some triple negative breast cancers can be treated successfully.
HER2+ve are tumours with HER2 receptors. About 20% of breast cancers are HER2+ve. HER2+ve breast cancer can be treated with HER2 targeted therapy. Before these drugs were available, HER2+ve breast cancers had poor prognosis.

Until the 1990s, the standard treatment approach for early breast cancer involved surgery followed by chemotherapy and radiotherapy. However, with the introduction of neoadjuvant chemotherapy, this paradigm shifted to account for different breast cancer subtypes. Initially, neoadjuvant chemotherapy was developed to convert inoperable tumors into operable ones and to shrink tumors for more conservative surgeries. As breast cancer subtypes became more clearly defined, oncologists identified two subtypes—triple-negative and HER2-positive breast cancers—that are most likely to respond to neoadjuvant chemotherapy. While current data show that neoadjuvant chemotherapy can prolong disease-free intervals, there is no conclusive evidence yet on improved overall survival. However, the benefits of improving success rate of conservation surgery and allowing response assessment makes neo-adjuvant therapy a preferred choice of treatment in selected cases.

In summary, with the growing understanding of the molecular subtypes of breast cancer, surgeons and oncologists are collaborating closely to develop personalized treatment plans for each patient. Oncologists are also working hand in hand with pathologists to accurately identify the specific
subtype of breast cancer, allowing for the most tailored systemic therapies to be provided.