Breast cancer is the most commonly diagnosed cancer in American women and, aside from skin cancer, the one primary care encounters most often. The great majority of cases today are found by screening mammography, at a point where the tumor is too small to feel and treatment is most effective. Most breast cancer is hormone-receptor-positive, which means it grows in response to estrogen and can be treated by blocking that signal. Men can develop breast cancer too, and although it is uncommon, a breast lump in a man deserves the same evaluation.
Risk Factors
- Age and sex: Being a woman and growing older are the two largest risk factors, and neither is modifiable. Most cases occur after age 50.
- Family history and inherited variants: A first-degree relative with breast or ovarian cancer raises risk, and inherited BRCA1 or BRCA2 variants raise it substantially. Our guide to BRCA genetic testing covers who should be tested.
- Reproductive history: Early first periods, late menopause, no pregnancies, or a first pregnancy after 30 each add a small amount of risk through longer lifetime estrogen exposure.
- Dense breast tissue: Dense tissue both raises risk modestly and makes mammograms harder to read, which is why density is now reported to patients.
- Alcohol, weight, and inactivity: These are the modifiable contributors. Risk rises with regular alcohol intake, and with obesity after menopause, when fat tissue becomes a significant source of estrogen.
Symptoms
Screening-detected cancers cause no symptoms at all, which is the point of screening. When symptoms do appear, the most common is a new, firm, painless lump. Others include a change in breast size or shape, skin dimpling or thickening that resembles orange peel, a nipple that newly turns inward, nipple discharge that is bloody or occurs without squeezing, persistent redness or scaling of the nipple, and a lump in the armpit. Breast pain alone is a common symptom and is rarely caused by cancer, but pain that is new, one-sided, and persistent still deserves an examination.
Screening and Early Detection
The US Preventive Services Task Force recommends screening mammography every two years for women aged 40 through 74; other bodies recommend starting annual screening at 40. Either schedule is defensible, and the choice is one to make with your doctor rather than from a headline. Women at high risk because of genetics, family history, or prior chest radiation may need to start earlier and add breast MRI. Our article on screening beyond the mammogram explains supplemental imaging, and cancer screenings by age puts breast screening alongside the others you are due for.
Diagnosis
An abnormal mammogram or a palpable lump leads to diagnostic imaging, usually a focused mammogram plus ultrasound. If the finding remains suspicious, a core needle biopsy provides tissue. The pathology report drives everything that follows: whether the cancer is invasive or confined to the ducts, its grade, and above all its receptor status. Estrogen and progesterone receptors and the HER2 protein are tested on every specimen, because those three results determine which treatments will work. A great many patients are told the results sound alarming when they are in fact favorable, so it is worth asking your oncologist to walk through the report line by line.
Treatment
Treatment is directed by an oncology team and almost always combines several approaches. Surgery removes the tumor, either as a lumpectomy or a mastectomy, and samples the nearby lymph nodes. Radiation usually follows lumpectomy. Chemotherapy is used when the cancer's biology or spread warrants it, and is increasingly avoided in lower-risk hormone-positive disease on the strength of genomic testing of the tumor.
For hormone-receptor-positive cancer, endocrine therapy is the long tail of treatment and the part primary care sees most. Tamoxifen blocks the estrogen receptor and is used in premenopausal women; after menopause an aromatase inhibitor such as anastrozole or letrozole lowers estrogen production instead. These are taken for at least five years. In higher-risk or advanced disease a CDK4/6 inhibitor such as abemaciclib or ribociclib is added. HER2-positive cancers are treated with antibody therapies directed at that protein, and capecitabine is among the oral chemotherapies used in some settings.
What Primary Care Handles
Oncology directs the cancer treatment; a great deal of what determines how the years go is managed here.
Side effects worth reporting rather than enduring
Aromatase inhibitors commonly cause joint stiffness and aching, and tamoxifen commonly causes hot flashes. Both are frequent reasons people quietly stop taking a medication that is preventing recurrence. Switching between agents often solves it, and there are effective options for hot flashes that do not involve estrogen. Any new leg swelling or pain, or unusual vaginal bleeding on tamoxifen, should be reported promptly rather than at the next scheduled visit.
Bones, heart, and everything that is not cancer
Aromatase inhibitors accelerate bone loss, so bone density is checked and osteoporosis treated when it appears. Cardiovascular disease remains a leading cause of death in breast cancer survivors, so blood pressure, cholesterol, and diabetes control matter as much during and after treatment as before it. Our endocrine care team coordinates this alongside your oncologist.
Survivorship and follow-up
After active treatment, follow-up settles into a clinical examination at intervals and annual mammography of any remaining breast tissue. Routine scans and tumor-marker blood tests are not recommended for symptom-free survivors, because they generate false alarms without improving outcomes. Fatigue, sleep disruption, fear of recurrence, and cognitive fog are common, real, and treatable.
When to Seek Care
Make an appointment for any new breast lump, a lump in the armpit, skin dimpling or thickening, a newly inverted nipple, spontaneous or bloody nipple discharge, or persistent nipple scaling. Do not wait for the next scheduled mammogram, and do not be reassured by a recent normal one, because a minority of cancers are not visible on mammography. The National Cancer Institute and MedlinePlus maintain plain-language overviews worth reading alongside anything you are told.
If you are due for a mammogram, unsure when to start, or have a family history you have never discussed with a doctor, schedule a visit.