Breast Cancer: Understanding risk, recognising changes and seeking care

By Dr Tariq Jagnarine

During Breast Cancer Awareness Month, conversations often focus on screening and finding a lump. For breastfeeding mothers, those conversations can be more complicated. The breasts naturally become fuller, firmer, and more sensitive during pregnancy and lactation, making it difficult to know which changes are expected and which need medical attention.
Breastfeeding is associated with a lower long-term risk of breast cancer. However, cancer can still develop during breastfeeding, and a persistent breast change should be assessed promptly. Supporting breastfeeding and investigating a concerning symptom can happen together.

How breastfeeding influences cancer risk
Breastfeeding is associated with a reduction in breast cancer risk, with longer cumulative breastfeeding duration generally linked to greater protection. Possible explanations include fewer menstrual cycles and changes in breast cells as they mature to produce milk. These biological effects may reduce the likelihood of some cells becoming cancerous.
This protection does not eliminate risk. A woman who breastfed all her children can still develop breast cancer. Equally, women who cannot breastfeed, or who stop earlier than planned, should never be blamed for a future diagnosis. Cancer develops through a combination of genetic, biological, and environmental factors.

Risk Factors: Who needs particular attention?
Increasing age is an important risk factor, although younger women can also develop breast cancer. Other factors include a personal history of breast cancer, certain previous abnormal breast biopsies, a strong family history, and inherited changes in genes such as BRCA1 and BRCA2. A history of breast or ovarian cancer on the father’s side of the family matters just as much as a history on the mother’s side.
Alcohol use, physical inactivity, and excess body weight after menopause can also increase risk. Some reproductive and hormonal factors influence risk, including early menstruation, later menopause and certain hormone treatments. Having a risk factor does not mean cancer is inevitable, and having no obvious risk factors does not mean a woman is protected.
Breast cancer does not usually have a single “trigger” comparable to the triggers of migraine. A stressful day, one meal, or a breastfeeding difficulty cannot explain a diagnosis. The useful discussion is about overall risk, breast changes, and timely assessment.

Signs and symptoms during breastfeeding
Many breast lumps during lactation have benign causes. These include inflammation, milk-filled cysts called galactoceles, and other noncancerous breast conditions. Infection can also cause pain, redness, and swelling. The important question is whether the finding resolves as expected or remains unexplained.
A new or persistent lump, thickening in the breast, or a lump in the armpit needs assessment. Other concerning changes include skin dimpling, a nipple that newly turns inward, persistent scaling around the nipple, unexplained bloody discharge, or a change in breast shape. Breast cancer may be painless, so the absence of pain should not provide false reassurance.
Rapid swelling, skin thickening, or redness that does not improve with appropriate treatment also requires review. Although infection is a common explanation during breastfeeding, inflammatory breast cancer can cause redness and swelling, sometimes without an obvious lump. Repeated treatment for presumed infection should not replace reassessment when the breast remains abnormal.

Diagnosis: Examination, imaging and biopsy
Assessment starts with a careful history and examination. I ask when the change began, whether it is growing, whether it changes after feeding, and whether there is fever, nipple discharge, or a family history of cancer. Both breasts and the surrounding lymph nodes should be examined.
Imaging may include ultrasound and diagnostic mammography, depending on the patient’s age and the findings. These tests can be performed while breastfeeding. Feeding or expressing milk shortly before imaging can reduce fullness and improve assessment. A suspicious symptom should not be left until the mother finishes breastfeeding.
When a finding is suspicious, a core needle biopsy may be needed to obtain tissue for examination. A scan can identify an abnormality, but tissue testing establishes whether it is cancer. If cancer is confirmed, the tissue is tested for oestrogen receptors, progesterone receptors and HER2. These results, together with the tumour’s size, grade and spread, help determine treatment.
Screening and diagnosis also serve different purposes. Screening looks for disease in someone without symptoms. A woman with a lump needs diagnostic assessment, even if she recently had a normal screening test.

Treatment and what it means for breastfeeding
Treatment depends on the cancer’s stage and biological characteristics. It may involve breast-conserving surgery, mastectomy, radiotherapy, chemotherapy, endocrine therapy, or targeted treatment.
Medicine names patients may encounter include doxorubicin, cyclophosphamide and paclitaxel as chemotherapy agents; tamoxifen or letrozole for appropriate hormone-sensitive cancers; and trastuzumab for suitable HER2-positive cancers. These medicines have different purposes and are selected by the oncology team according to the individual diagnosis.
Breastfeeding should not continue during cytotoxic chemotherapy because the medicines can enter breast milk and harm the baby. Breastfeeding is also avoided during tamoxifen treatment. Other endocrine, targeted and immune treatments require drug-specific advice, including how long to wait after the last dose before considering breastfeeding again. Expressing and discarding milk does not make it safe to feed the baby between doses without specialist guidance.
During radiotherapy to one breast, feeding from that breast should be avoided. Feeding from the unaffected breast may be possible when the rest of the treatment plan allows it. Surgery and radiotherapy can reduce milk production on the treated side, so any feeding plan should include monitoring of the baby’s intake and growth.
Treatment should not be delayed to prolong breastfeeding. When feeding must stop, the mother needs practical and emotional support, including a safe alternative feeding plan.

Prevention and breast health
Breastfeeding is one way to reduce risk, alongside regular physical activity, maintaining a healthy weight and limiting or avoiding alcohol. The World Health Organisation (WHO) recommends exclusive breastfeeding for the first six months, followed by appropriate complementary foods with continued breastfeeding for up to two years or beyond, when medically appropriate. Mothers need support to achieve these goals, particularly when returning to work.
Know what is usual for your breasts and report a persistent change. Follow the screening plan appropriate to your age and risk. Women with a strong family history may need specialist risk assessment and genetic counselling. Some women at particularly high risk may be offered preventive medication, such as tamoxifen, but this requires specialist assessment and is not suitable during breastfeeding.
In primary care, my concern is the delay that can occur when every breast change is attributed to breastfeeding. A mother may be focused on her baby, reluctant to interrupt feeding, or frightened that an investigation will force her to stop. Those concerns deserve a clear explanation and a practical plan.
My approach is to examine the finding, investigate when needed, and arrange follow-up until there is a satisfactory explanation. If a presumed infection does not improve, we must reassess. If a lump persists, reassurance alone is insufficient.
A mother’s health matters alongside her baby’s health. Breastfeeding deserves support, and a persistent breast change deserves timely attention. During this awareness month, that is the message I want every family to remember.