Appetite changes, whether it's loss of appetite or feeling full too quickly, are not something that should be taken lightly. "Early satiety means that you have a poor appetite and feel full after only a small amount of food," Dr. Phillips says. "Cancers of the abdomen (eg. intestinal cancers, ovarian cancers) as well as an enlarged spleen, which is associated with some blood cancers, may actually be the culprit." While there may be other gut issues that can be to blame, it never hurts to get it checked out.

"If your weight loss occurs without change in diet or exercise, it may be an early warning sign of cancer, most commonly pancreatic, stomach, esophageal, or lung cancer," Dr. Phillips says. "In these conditions, weight loss is the result of an imbalance in metabolism — essentially the energy the cancer demands is not being replaced." Again, if you have concerns, it's best to see a doctor.

There are number of reasons your gums could be bleeding — brushing your teeth too vigorously, for example — but in some cases, gum bleeding can also be a sign of leukemia. "With leukemia, your blood platelets — the cells that stop your body from bleeding — may be low, making it harder for you to stop bleeding in different parts of your body, including your gums," Dr. Phillips says. "Also, some leukemias cause your gums to become swollen and bleed more easily."

Cramping during your period is common, but if you're experiencing persistent, painful pelvic cramping, see a doctor. "Pelvic cramping in women is often explained away as normal hormonal changes, constipation, or an upset stomach, but it can be a warning sign of ovarian cancer, especially if combined with bloating," Marleen I. Meyers, MD, medical oncologist at Perlmutter Cancer Center, tells Bustle. If cramping doesn't seem to go away, it may be best to check in with your OB/GYN.

Regularly bleeding after sex is another symptom you should be sure to look into. "Many people feel this is normal, especially if someone has irregular periods or vaginal dryness," Dr. Meyers says. "But this may be a sign of cervical cancer."

Headaches are very common and are not always associated with a tumor, but changes in frequency, type, or intensity of headaches should prompt neurological evaluation. "Headaches typically are due to the tumor size and growth rate," neuro-oncologist and neuroscientist Santosh Kesari, MD, PhD, tells Bustle. "So larger tumors and faster-growing tumors cause an increase in pressure in the brain, resulting in activation of pain receptors on the coverings of the brain, resulting in a headache. The brain itself has no pain receptors. A small, fast-growing tumor can cause as severe of a headache as a large, but slow-growing tumor."

Some signs of cancer can be cognitive as well. "Patients can be present with forgetfulness and short-term memory loss, and it usually suggests involvement of temporal or frontal lobes of the brain where memory functions reside," Dr. Kesari says. "Sometimes it can occur over months to years, and [the person is] thought to have a dementia condition before imaging is done to reveal a brain tumor."

Although it's not always the case, changes in your nipple, areola, or skin of your breast can be a sign of breast cancer. "These include a retraction or inward pulling of any of these structures, discoloration, or a change in texture such as puffiness," Richard Reitherman, MD, PhD, medical director of breast imaging at MemorialCare Breast Center, tells Bustle. "These changes may be noticeable only in certain positions relative to gravity, so it is important to check for this category of change when you are lying down on your back, rolling side to side, bending over, or upright facing a mirror while positioning your hands behind your neck."

If you experience any of these symptoms, be sure to see your doctor for evaluation. There are many cases where they don't indicate cancer, but it's always worth it to get checked.