Breast Cancer: Signs, Symptoms & Risk Factors
October is Breast Cancer Awareness Month
Breast cancer most commonly occurs in women age 50-69, although it can occur in older or younger women; in rare cases, men can also get breast cancer.
A 2022 breast cancer study funded by the World Health Organization indicates that breast cancer (primarily in women) is the most commonly diagnosed malignancy worldwide, thus representing an important cause of premature mortality in women. The study predicts that due to population growth and aging, a worldwide growth by 2040 of 40% in newly diagnosed breast cancer cases, and 50% in deaths from breast cancer.
In Canada, 25% of new cases of cancer in women are breast cancer, which accounts for 13% of all cancer deaths in Canadian women (Government of Canada).
What is Breast Cancer?
Adenocarcinoma is the most common type of breast cancer, and occurs when malignant tumours begin in the glandular tissues of the breast – in milk ducts (ductal cancers) or milk glands (lobular cancers) that are found in the upper, outer part of the breast. There are many other types of breast cancer as well, and both the Canadian Cancer Society (CCS) and American Breast Cancer Foundation (ABCF) have a wealth of additional information on this topic.
Early Signs & Symptoms of Breast Cancer
The most common early sign of breast cancer is a lump in the breast. Although most lumps in the breast are not cancerous, they should never be ignored. Even if there are no breast lumps that can be seen or felt during a physical examination, you may still have breast cancer. Regular self-examinations, doctor check-ups, and mammograms can help detect breast cancer in it’s earliest stages. If you notice any of the changes below to your breasts, consult your doctor.
- Breast lumps that can be felt, seen, or identified on a sensitive mammogram and:
- don’t go away or get smaller.
- can’t be moved or feel attached to chest wall or skin.
- are hard or irregular in shape.
- Note: lumps that are tender or painful are more likely to be benign; painless lumps are more likely to be cancerous
- Changes in breast shape or size
- Armpit lumps / swollen lymph nodes
- small, hard lumps (could be either painful or painless) in the armpit may be a sign of breast cancer that has spread to lymph nodes
- Breast skin or nipple changes
- Breast or nipple pain
- Redness, heat, swelling, or itchiness (which may/may not be relieved by topical solutions) may be signs of inflammatory breast cancer
- Puckering, dimpling, or thickening of the breast skin or nipple
- Nipple becomes inverted/turns inwards (nipple retraction)
- Nipple discharge, especially if it is only from one breast and appears spontaneously (without pressure on the nipple), or is bloody.
- Nipple crusting, scaling, or ulcers may be a sign of rare types of breast cancer.
Breast Cancer Risk Factors
Breast cancer may (or may not) occur whether the most common risk factors below are present or not, but their presence has been proven to increase the risk factor for developing breast cancer:
Genetic/Reproductive Risk Factors
- Sex and Aging – Senior or older women aged 50-69 are at the highest risk of developing breast cancer, with 2/3 of breast cancers occurring in women age 55+ (ABCF). According to the Canadian Cancer Society, women are more at risk because their breasts are exposed to the female hormones estrogen and progesterone, which stimulate the growth of some breast cancers.
- Location/Race/Heritage – Breast cancer is most common in high-income, developed countries such as Canada, the United States and some European countries like Great Britain. This may also be a reflection of heritage/genetic factors. The ABCF says that Caucasian women are at higher risk of getting breast cancer while the risk of getting breast cancer is lower in Asian, Hispanic, and Native American women.
- Personal History – If you have had breast cancer before, you have an increased risk of getting breast cancer again. Having other cancers before also increases your risk of breast cancer.
- Ionizing Radiation Exposure – Cancer patients that have had exposure to ionizing radiation, including radiation therapy to the chest, neck, and armpit, are at higher risk of getting breast cancer. The younger the age of this exposure, the higher the risk.
- Family History – If your family members have had breast cancer, or other types of cancer. According to CCF, having one first-degree relative (mother, sister, daughter) with breast cancer approximately doubles a woman’s risk; the more first-degree relatives with breast cancer, the greater the risk.
- Genetics/BRCA Gene Mutations – The American Breast Cancer Foundation says that 5-10% of breast cancers are hereditary. Although there are other rare genetic risk factors, the BRCA1 and BRCA2 gene mutations are the most common causes of hereditary breast cancer (1 in 500 women have the BRCA1 or BRCA2 genes) and women of Ashkenazi Jewish heritage (Eastern European) are at higher risk of having the BRCA1 or BRCA2 genes (1 in 40). CCF says studies have shown that women with inherited BRCA1 or BRCA2 gene mutations have up to an 80% chance of developing breast cancer in their lifetime. Women with these inherited mutations also have a higher risk of developing breast cancer at a younger age (usually before menopause), and of developing ovarian cancer. Genetic testing can determine if you have the BRCA1 or BRCA2 genes.
- Dense Breasts – Breasts that have more supportive or gland tissues (that make and drain milk), and less fatty tissues, are said to be dense. Breast density can be inherited, and can be identified with a mammogram.
- Early menstruation / Late Menopause – Women who had their first period age 11 or younger (early menstruation), and/or women whose periods stopped after age 55 (late menopause), will have had their cells exposed to hormone estrogen for longer periods of time, thus increasing their risk factor for developing breast cancer.
- No Pregnancies/Late Pregnancy – The number of pregnancies and timing of pregnancies influence the risk factors for breast cancer, because pregnancy interrupts/reduces the number of menstrual cycles and reduces the exposure of breast cells to estrogen. The earlier you have a pregnancy (ie, before age 20), and the more pregnancies you have, the less risk you have of getting breast cancer. No pregnancy or pregnancy after the age of 30 increase the risk of breast cancer. Studies have shown that breastfeeding can reduce the risk of breast cancer because it reduces the number of menstrual cycles.
- Hormone Replacement Therapy/HRT – Long-time HRT for menopause, especially Combined HRT (uses estrogen plus progestin), can increase your risk of developing breast cancer.
- Oral Contraceptives With Estrogen and Progesterone – While taking oral contraceptives that contain both estrogen and progesterone, your risk of getting breast cancer is increased. When you stop taking them, this risk factor disappears.
- Tall Height – Taller adult women are at higher risk of getting breast cancer after menopause. This may be affected by their socio-economic status and environmental factors earlier in life, which in turn influenced diet and nutrition and impacted their height/growth.
Lifestyle Risk Factors
Drinking Alcohol – Even low levels of alcohol consumption (over 1 drink/day) increase your risk factor for breast cancer. Alcohol may lower levels of essential nutrients and cause higher levels of estrogen.
Obesity/Overweight – Women with a BMI of 31.1 or higher are at higher risk of getting breast cancer (2.5 x greater than women with a BMI of 22.6 or lower). Having more fat tissue can increase estrogen levels, thus increasing the risk of breast cancer developing.
Physical Inactivity – Some studies have shown that the less physical activity you have, the higher the risk of getting breast cancer.
Smoking – Studies have also shown a link between smoking and breast cancer for women.
Note: This article was first published in 2016; it has been updated with new/additional content.
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