Does caffeine cause breast cancer?

What did the WHO find about coffee and cancer?

In June 2016, 23 scientists brought together by IARC, the cancer agency of the World Health Organization, reviewed more than 1,000 studies in humans and animals. They found inadequate evidence that drinking coffee causes cancer overall.

Coffee was placed in Group 3, “not classifiable as to its carcinogenicity to humans”. This replaced an older 1991 rating of “possibly carcinogenic to humans” (Group 2B).

Many studies showed coffee drinking had no cancer-causing effect for cancers of the pancreas, female breast and prostate. Lower risks were seen for cancers of the liver and the lining of the womb (endometrium). For more than 20 other cancers, the evidence was inconclusive.

Source: WHO cancer agency (IARC): Press release No. 244 – coffee, maté and very hot beverages (2016)

What about tea and caffeine?

The 2016 review covered coffee, maté (an infusion of dried leaves drunk mainly in South America) and very hot drinks. It did not rate tea or caffeine on their own.

Its main warning was about temperature. Drinking very hot drinks, above 65°C, was rated “probably carcinogenic to humans” (Group 2A) because of a link with cancer of the oesophagus (food pipe). The studies came from places where tea or maté is traditionally drunk at about 70°C. IARC’s director said it is the temperature, rather than the drinks themselves, that appears to be responsible.

Source: WHO cancer agency (IARC): Press release No. 244 – coffee, maté and very hot beverages (2016)

Can caffeine make breasts sore?

NHS hospital leaflets differ on whether cutting caffeine eases sore breasts. Royal United Hospitals Bath says cutting down alcohol or caffeine does not seem to help breast pain. Gateshead Health lists cutting down on caffeine among lifestyle changes that may help. Neither leaflet links caffeine to breast cancer.

The NHS says breast pain is usually linked to periods, and that breast pain by itself is unlikely to be a symptom of cancer.

Sources: Royal United Hospitals Bath NHS Foundation Trust: Breast pain (mastalgia) leaflet; Gateshead Health NHS Foundation Trust: Breast pain leaflet; NHS: Breast pain

What does raise breast cancer risk?

The NHS says you may be more likely to get breast cancer if you are over 50, have dense breast tissue, have close family who have had breast or ovarian cancer, have certain breast conditions or have higher hormone levels. To lower your chance, it suggests:

• cutting down on alcohol and avoiding drinking more than 14 units a week
• losing weight if you are overweight
• stopping smoking

The World Health Organization also lists harmful use of alcohol among the factors that increase breast cancer risk. Coffee and tea are not on either list.

Sources: NHS: Causes of breast cancer in women; World Health Organization: Breast cancer fact sheet

Which breast changes should you get checked?

Whatever you drink, the NHS says to see a GP or doctor if you notice:

• a lump or swelling in your breast, chest or armpit
• a change in the skin of your breast, such as dimpling (it may look like orange peel)
• a change in skin colour – on white skin it may look red, on black or brown skin it may look darker than usual
• a change in the size or shape of one or both breasts
• nipple discharge (if you are not pregnant or breastfeeding), which may have blood in it
• a change in the shape or look of your nipple, such as it turning inwards or a rash on it

If your symptoms are caused by cancer, finding it early may mean it is easier to treat.

Source: NHS: Symptoms of breast cancer in women