From cysts to size, here's what you need to know about keeping your breasts healthy.

1. All lumps are not created equal
If you've ever felt a lump or bump in your breast, you'll know the sick feeling it can instantly cause in the pit of your stomach. But don't panic yet: There are lots of things it could be besides breast cancer. "Very often I will see premenopausal women with palpable breast masses that turn out to be cysts or benign [noncancerous] lumps called fibroadenomas," says Melinda Wu, a family physician with Women's College Hospital in Toronto who has worked at both the Henrietta Banting Breast Centre and the Princess Margaret Hospital Breast Clinic.

If the lump is suspicious, your doctor will typically do a clinical exam and order a diagnostic mammogram and ultrasound. Sometimes lumps require biopsies, but 80 percent of biopsied lumps turn out to be benign, explains Wu. That doesn't mean you shouldn't be mindful; get to know your breasts and have any lumps checked out. According to the Breast Cancer Society of Canada, breast cancer affects one in nine women, with 23,800 women estimated to be diagnosed in 2013. And the risk increases as you age.

2. Get the 411 on cysts
Breast cysts (fluid-filled sacs) are exceedingly common in premenopausal women in the 35 to 50 age group. While cysts aren't linked to an increased risk of breast cancer, if you have a complicated cyst (one that has a solid component to it), your doc should monitor it using ultrasounds to ensure the size remains stable – especially if you are postmenopausal. Also, remember that cysts tend to grow in size and tenderness leading up to your period as your hormone levels fluctuate.

3. Breast pain is usually normal
"Lots of women come to us about breast pain, and we often don't know what causes it," says Wu. "But we do know that breast pain is not a marker for breast cancer." For some people, pain is caused by deep breast cysts. Of course, if the pain is persistent, you should see your family doctor to make sure it's nothing more serious. Lifestyle changes such as limiting alcohol, increasing water intake, exercising regularly and wearing a properly fitted bra can all help with breast pain, says Wu.

4. Your breasts will change with age
To add insult to aging, as you get older your breasts become less dense and more fatty. But there's a positive side to this: The reduced density makes it easier to spot any problems on a mammogram. "The reasons we generally don't do mammograms in young women are because the incidence of breast cancer is very low in this population and because breast tissue is dense and mostly glandular as it's preparing for breast-feeding," explains Dr. May Lynn Quan, an associate professor of surgery and oncology at the University of Calgary and the surgical lead for the Alberta Health Services Calgary Breast Health Program. Mammograms are X-rays, she says, so they pick up things that are dense, such as bones, glandular tissue and tumours.

When should you start getting screened? For the average woman without a family history or risk factors for breast cancer, Wu recommends having a mammogram every two years, starting at age 50; at 40, have a discussion with your family doctor about breast screening. (Risk factors include having certain kinds of noncancerous breast lumps, starting menstruation before age 12 and menopause later than 55, smoking, drinking excessively, and never having children or having children after 30.) Take note: It's important to go to the same mammogram centre each time so your results can be compared with your previous screenings, says Wu.

5. You can't really change your breast size
Despite Frenchy's comical attempts in Grease to make her breasts bigger with exercise, it doesn't work that way. Breasts are not muscular; they're organs with connective tissue that fits together to make their infrastructure. When you do muscle training, you are targeting your pectoral muscles, which lie underneath your breasts. Your natural breast size is not based purely on your mom's bustiness, says Wu. There is a reliable breast size pattern, but it doesn't necessarily come from one side of the family, she says. Multiple factors affect how big your breasts become (not to mention weight fluctuations and pregnancy, which can make them more pendulous and elongated). And if your breasts aren't perfectly symmetrical, you're definitely not alone. "It's just how you are made," says Wu. It's common to have one breast or nipple that is larger or otherwise different; it's only an issue if the asymmetry has developed recently. If one of your breasts is hot or swollen, see a doctor ASAP.

6. Your breasts have a tail
OK, so they don't have an actual tail, but the tissue that leads into your armpit in a teardrop shape is called a "breast tail." Women tend to have a lot of dense tissue in the upper outer quadrants of their breasts. It carries up into the armpits, near some of the lymph nodes, which are a separate entity from your breasts. However, just as the lymph nodes in your neck can swell when you have a sore throat, the ones in your armpits can swell if there is a problem with your breasts, says Wu, so pay attention to any swelling there that doesn't dissipate.

7. You may have a third nipple
All joking aside, doctors do see this from time to time. These extra­mammary nipples are not uncommon and may or may not be connected to your milk ducts. You may not even know you have one, because it won't necessarily look like a nipple; people often think it's a mole, explains Wu. Picture the milk line on the underside of a cat; you can look for them in the same area on your own torso, as well as in your armpits.

8. Cancer is not all in your genes
While Angelina Jolie may have had a high breast cancer risk due to the BRCA1 gene, "most women who walk through my door have no risk factors besides being a woman and being postmenopausal," says Quan. "Twenty-five percent of women will have a family history of some sort, and only five to 10 percent of women will have breast cancer because of a gene mutation." If multiple people on both sides of your family have had breast cancer, you can seek counselling from a genetic specialist to figure out your next steps.

9. Your weight affects your overall breast health
Staying in shape isn't just about fitting into your skinny jeans. Maintaining a low amount of abdominal fat is key for cancer survivors and women who are at high risk for developing breast cancer, says Wu. "People tend to make estrogen from abdominal fat, and the ovaries stop producing estrogen through menopause," says Wu. "A higher weight means more estrogen, which can lead to more lumps and bumps." She recommends decreasing your overall BMI, and Quan agrees. "For women who have had cancer, the one thing we know is that weight gain has been associated with higher rates of recurrence," she says. If that's not motivation to hit the gym, we don't know what is.

10. Nipples can be a key breast health indicator
Think of your breasts like inverted trees, says Quan, with multiple ducts branching from your nipples. The key function of your breasts is to make milk, so some discharge can be normal. If you have discharge coming out of only one duct in one breast, it means it's coming from a specific duct on the tree – which can be concerning, says Quan. "We worry when nipple discharge is only on one side, if it's bloody, if it happens on its own (without squeezing), if there is a family history of breast cancer or if there's a palpable lump," says Wu. Also, if one nipple suddenly inverts or you have a rash around the areola, get it checked out, as these can be indicative of cancer.