Surgery removes the visible cancer from the breast and, where involved, the lymph nodes. But for many patients, surgery alone is not sufficient. Even when the operation appears completely successful, there is always the possibility that microscopic cancer cells have escaped into the bloodstream or lymphatic system and taken up residence elsewhere in the body before the primary tumour was removed.

Adjuvant therapy refers to the treatments given after primary cancer surgery specifically to reduce this risk. The word "adjuvant" comes from the Latin for "to help," and that is precisely what these treatments do — they work alongside surgery to improve the overall chance of cure by targeting any residual disease that cannot be seen or detected with current imaging.

For breast cancer, adjuvant therapy is not a single treatment. It is a combination of therapies, selected and sequenced based on the biology of your specific cancer, your staging, your overall health, and your personal circumstances. At Breast & Surgical Oncology at The Poche Centre, adjuvant therapy planning is made by the full multidisciplinary team and discussed transparently with every patient before treatment begins.

Neoadjuvant Therapy: Treatment Before Surgery

Before exploring adjuvant treatments given after surgery, it is important to clarify an important and increasingly common approach: neoadjuvant therapy. This refers to systemic treatment given before surgery rather than after.

Neoadjuvant therapy is recommended in several situations. It can shrink a large tumour to make breast-conserving surgery possible where mastectomy would otherwise have been required. It allows assessment of how the tumour responds to systemic treatment in real time, which provides valuable prognostic information and can guide post-surgical treatment decisions. For HER2-positive and triple-negative breast cancers in particular, a complete pathological response to neoadjuvant treatment (meaning no residual cancer found in the surgical specimen) is associated with an excellent prognosis.

Whether treatment is given before or after surgery, the goals are the same: to reduce the risk of the cancer returning and to improve long-term survival. The sequencing is a clinical decision made by your multidisciplinary team in the context of your specific situation.

How Adjuvant Therapy Decisions Are Made

Determining which adjuvant therapies are appropriate for you is one of the most important conversations you will have with your oncology team. It is not a one-size-fits-all decision, it is a highly personalised assessment that takes into account multiple factors.

Tumour biology is the foundation of adjuvant therapy planning. The information provided by your biopsy and surgical pathology report, including tumour type, grade, receptor status (oestrogen, progesterone, and HER2), and Ki-67 (a measure of how rapidly the cancer cells are dividing), directly determines which therapies are likely to be effective and beneficial for your cancer.

Stage and lymph node status provide important context. The size of the tumour, whether lymph nodes were involved, and how many, all influence the risk of recurrence and therefore the magnitude of benefit from adjuvant treatment.

Genomic testing has transformed adjuvant decision-making for a significant proportion of patients. For early-stage, hormone receptor-positive, HER2-negative breast cancers, genomic tests such as Oncotype DX and Prosigna analyse the activity pattern of multiple genes within the tumour to generate a recurrence score that predicts both the likelihood of distant recurrence and whether chemotherapy is likely to add meaningful benefit over hormonal therapy alone. This means some patients who would previously have received chemotherapy can now safely avoid it, while others can be more confidently directed toward treatment that will genuinely help them. Our team incorporates genomic testing into treatment planning where it is clinically appropriate.

Your overall health and personal circumstances also matter. The benefits and side effects of adjuvant treatments are weighed in the context of your age, fitness, other health conditions, and your own values and preferences. Treatment decisions are always a conversation, not a prescription.

Types of Adjuvant Therapy in Breast Cancer

Chemotherapy

Chemotherapy uses medicines that are toxic to rapidly dividing cells, given intravenously or orally, to destroy cancer cells throughout the body. In the adjuvant setting, chemotherapy is given after surgery to eliminate any microscopic residual disease. In the neoadjuvant setting, it is given before surgery to shrink the tumour and treat systemic disease early.

Adjuvant chemotherapy is most clearly beneficial for tumours that are high grade, hormone receptor-negative, HER2-positive, or where the lymph nodes are involved. For hormone receptor-positive, HER2-negative cancers, genomic testing increasingly guides the decision. Chemotherapy regimens for breast cancer typically involve several cycles administered over three to six months.

Radiotherapy

Radiotherapy uses targeted, high-energy radiation to destroy any cancer cells remaining in the breast, chest wall, or regional lymph nodes after surgery. It is most commonly recommended after breast-conserving surgery (lumpectomy), where it reduces the risk of local recurrence in the remaining breast tissue and is a key reason that lumpectomy achieves equivalent long-term survival outcomes to mastectomy. It is also recommended after mastectomy in specific circumstances, including when the tumour was large, when lymph nodes were involved, or when surgical margins were close.

Radiotherapy is administered as an outpatient treatment, typically over three to six weeks following completion of surgery and, where applicable, chemotherapy.

Hormonal (Endocrine) Therapy

Hormonal therapy is recommended for cancers that are oestrogen receptor-positive (ER-positive) and/or progesterone receptor-positive (PR-positive), which account for the majority of all breast cancers. These cancers are driven by oestrogen, and hormonal therapy works by either reducing the level of oestrogen in the body or blocking oestrogen from binding to cancer cell receptors, depriving the cancer of the stimulus it needs to grow.

Hormonal therapy is typically taken as a daily oral tablet for a minimum of five years, and often for ten years, following primary treatment. It is one of the most effective adjuvant treatments available for hormone receptor-positive breast cancer and significantly reduces the risk of recurrence.

The main hormonal therapy agents used in breast cancer include tamoxifen, which blocks oestrogen receptors and is used in premenopausal women and sometimes in postmenopausal women; aromatase inhibitors including anastrozole, letrozole, and exemestane, which block the production of oestrogen in postmenopausal women and are often more effective than tamoxifen in this group; and ovarian suppression (using GnRH agonists such as goserelin), which is used in younger premenopausal women to suppress ovarian oestrogen production and is often combined with tamoxifen or an aromatase inhibitor.

Targeted Therapy

Targeted therapies are drugs designed to interfere with specific molecular pathways that cancer cells depend on for growth and survival. In breast cancer, the most clinically important targeted therapies are those directed against the HER2 protein.

HER2-positive breast cancers overexpress the HER2 receptor on the surface of cancer cells, which drives aggressive tumour growth. Anti-HER2 therapies specifically block this receptor, preventing it from signalling and stimulating cancer cell proliferation. Trastuzumab (Herceptin) is the foundational anti-HER2 therapy and has dramatically improved outcomes for HER2-positive breast cancer since its introduction. It is given intravenously over twelve months in the adjuvant setting. Pertuzumab is a second anti-HER2 antibody increasingly used alongside trastuzumab for higher-risk HER2-positive cancers. For patients whose tumour did not achieve a complete pathological response to neoadjuvant treatment, trastuzumab emtansine (T-DM1), an antibody-drug conjugate, is used in the adjuvant setting to reduce the risk of recurrence.

Other targeted agents used in breast cancer adjuvant treatment include CDK4/6 inhibitors (such as abemaciclib) for high-risk hormone receptor-positive cancers, PARP inhibitors (such as olaparib) for patients with a BRCA1 or BRCA2 mutation and early-stage breast cancer, and everolimus in selected settings.

Immunotherapy

Immunotherapy works by harnessing the body's own immune system to recognise and attack cancer cells. In breast cancer, immunotherapy is most established for triple-negative breast cancer, where immune checkpoint inhibitors (such as pembrolizumab) have shown significant benefit in both the neoadjuvant and adjuvant settings in specific patient groups. The role of immunotherapy in breast cancer continues to expand rapidly as clinical trial data matures.

The Multidisciplinary Approach to Adjuvant Planning

Targeted therapies are drugs designed to interfereAt Breast & Surgical Oncology at The Poche Centre, adjuvant therapy planning is not determined by a single clinician. Every patient's case is reviewed at a multidisciplinary team (MDT) meeting attended by breast surgeons, medical oncologists, radiation oncologists, radiologists, and pathologists. This team-based review ensures that your adjuvant treatment plan reflects the combined expertise of the full oncology team, is informed by the latest clinical evidence and trial data, and is tailored to your specific tumour biology and clinical situation.

Following the MDT meeting, your surgeon and medical oncologist will meet with you to discuss the recommended plan, explain the rationale for each component, answer your questions, and ensure you feel genuinely informed before any treatment begins. There is always time to ask questions, to seek a second opinion, and to discuss your concerns. These decisions matter enormously, and we take the time they deserve.

Your Adjuvant Therapy at The Poche Centre

Our surgeons work in close collaboration with a network of specialist medical and radiation oncologists across our hospital network, ensuring that the transition from surgery to adjuvant treatment is seamless and well-coordinated. We remain involved in your care throughout the adjuvant treatment period, not just during the surgical phase, and we are always available to discuss any concerns that arise.