Caffeine consumption does not appear to be associated with overall breast cancer risk, according to a report in the October 13, 2008 issue of Archives of Internal Medicine, one of the JAMA/Archives journals. However, there is a possibility of increased risk for women with benign breast disease or for tumors that are hormone-receptor negative or larger than 2 centimeters.

Caffeine is probably the most commonly consumed drug worldwide, present in coffee, tea, chocolate and some medications, according to background information in the article. It was hypothesized that caffeine may increase the risk of breast cancer after a study showed that women with non-cancerous breast disease experienced relief from their symptoms after removing caffeine from their diet.

Ken Ishitani, M.D., Ph.D., of Brigham and Women's Hospital and Harvard Medical School, Boston, and Tokyo Women's Medical University, Japan, and colleagues studied 38,432 women 45 years or older who provided dietary information in 1992-1995. Over an average of 10 years of follow-up, 1,188 of the women developed invasive breast cancer.

"Consumption of caffeine and caffeinated beverages and foods was not statistically significantly associated with overall risk of breast cancer," the authors write. Among women with benign breast disease, a non-significant positive association with breast cancer risk was observed for those in the highest quintile (one-fifth) of caffeine consumption and a significant association was observed for those in the highest category of coffee consumption (four cups or more daily).

Consuming caffeine was also associated with a 68 percent increased risk of estrogen receptor-negative and progesterone receptor-negative breast cancer, or tumors to which the hormones estrogen and progesterone do not bind, and a 79 percent increased risk for breast tumors larger than 2 centimeters.

"The mechanisms by which caffeine may affect breast carcinogenesis [cancer development] are complex and remain unclear," the authors write. "In the present investigation, caffeine consumption was associated with increased risk of breast cancers negative for both estrogen receptors and progesterone receptors or larger than 2 centimeters, which have less favorable prognoses. These findings indicate that caffeine consumption may affect breast cancer progression, and such an effect may be independent of the estrogen pathway." Further study is required to better understand caffeine's role, they note.(Arch Intern Med. 2008;168[18]:2022-2031).

• Ductal carcinoma in situ (DCIS): This is the most common type of non-invasive breast cancer (85 - 90% of all cases). DCIS means that the cancer is only in the ducts. It has not spread through the walls of the ducts into the tissue of the breast. Nearly all women with cancer at this stage can be cured. Often the best way to find DCIS early is with a mammogram.
• Lobular carcinoma in situ (LCIS): This condition which occurs in approximately 8% of all cases, begins in the milk-making glands but does not go through the wall of the lobules. Although not a true cancer, having LCIS increases a woman's risk of getting cancer later. For this reason, it's important that women with LCIS to follow the screening guidelines for breast cancer.
  

• Inflammatory breast cancer (IBC): This uncommon type of invasive breast cancer accounts for about 1% to 3% of all breast cancers. Usually there is no single lump or tumor. Instead, inflammatory breast cancer (IBC) makes the skin of the breast look red and feel warm. It also gives the skin a thick, pitted appearance that looks a lot like an orange peel. Doctors now know that these changes are not caused by inflammation or infection, but by cancer cells blocking lymph vessels in the skin. The breast may become larger, firmer, tender, or itchy. IBC is often mistaken for an infection in its early stages. Because there is no defined lump, it may not appear on a mammogram, which may make it even harder to catch it early. It usually has a higher chance of spreading and a worse outlook than invasive ductal or lobular cancer.
• Paget's disease of the nipple. Paget's disease of the nipple or breast is a rare type of breast cancer, which can occur in women and men. It shows up in and around the nipple, and usually signals the presence of breast cancer beneath the skin. Most cases are found in menopausal women, but can also appear in women that are as young as 20. Early stages symptoms include redness, scaly and flaky, and mild irritation of nipple skin. Advanced stages may include: tingling in nipple skin, very sensitive skin on the nipple, burning or painful nipple skin, ooze or bloody discharge from the nipple (not milk), itchiness that doesn't respond to creams, nipple retraction (pulls into the breast), scaly rash on areola skin, and/or breast lump beneath the affected skin.

 There are also many other less common types of breast cancer.

• a lump or a thickening in the breast or in the armpit. Note Most breast lumps are benign (be-nine); that is, they are not cancer. Benign breast tumors are abnormal growths, but they do not spread outside of the breast and they are not life threatening. But some benign breast lumps can increase a woman's risk of getting breast cancer. Most lumps turn out to be caused by fibrocystic (fi-bro-sis-tik) changes. Cysts are fluid-filled sacs. Fibrosis is the formation of scar-like tissue. Such changes can cause breast swelling and pain. The breasts may feel lumpy, and sometimes there is a clear or slightly cloudy nipple discharge.
• a change of size or shape of the mature breast
• fluid (not milk) leaking from the nipple
• a change of size or shape of the nipple
• a change of color or texture of the nipple or the areola, or of the skin of the breast itself (dimples, puckers, rash)
• a discharge from the breast