context: How can you tell something's not quite right? Pay attention to the clues from your body. Play it smart when you notice anything that could be a serious health problem, like cancer. Talk to your doctor and get it checked out. In general, disease is easier to treat when you spot it early. Appetite loss. Many conditions, from depression to the flu, can make you feel less hungry. Cancer can have this effect by changing your metabolism, the way your body turns food into energy. Stomach, pancreatic, colon, and ovarian cancers also can put pressure on your stomach and make you feel too full to eat. Blood in the stool. Cancers can bleed, but so can a bunch of other things, like ulcers, hemorrhoids, infections, or a sore. When you see red in your poop, the blood is often from somewhere in your GI tract, meaning your esophagus, stomach, or intestines. One way to tell where the blood is coming from is by how light or dark it looks. Bright red could mean the bleeding is in your rectum or the end of your intestines. A darker color means it may be from higher up, like a stomach ulcer. No matter what the cause, blood in your stool needs to be checked out. You may need a colonoscopy or other tests to find the problem. Blood in the urine. When it shows up in your pee, blood could be a warning sign of a problem in your urinary tract. Kidney or bladder cancer can cause this symptom, but it could also be due to an infection, kidney stones, or kidney disease. Cough that doesn't go away. A cold or the flu can make you hack away, but it's also a potential symptom of lung cancer, along with red flags like chest pain, weight loss, hoarseness, fatigue, and shortness of breath. See your doctor if you can't seem to shake it, especially if you're a smoker. Extreme fatigue. It's one of the most common cancer symptoms. We're not talking about a normal type of tiredness here -- it's exhaustion that doesn't go away. If changing your activity level or getting more sleep doesn't make you perk up, see your doctor. Fever that doesn't go away. When your temperature goes up, it's usually a sign you've caught an infection. But some cancers, including lymphoma, leukemia, and kidney and liver cancers, can also make that happen. Cancer fevers often rise and fall during the day, and sometimes they peak at the same time. See your doctor if you have a temperature of over 100.5 degrees F that lasts for more than a few days. Lump in the neck. It could be an infection, but it's also an early warning of mouth, throat, thyroid, and voice box (larynx) cancers. Cancer lumps usually don't hurt. If you have one that doesn't go away or grows, see your doctor. Night sweats. In middle-aged women, it can be a symptom of menopause, but it's also a symptom of cancer or an infection. Skin changes. A telltale sign of skin cancer is a growth that starts to look different or a sore that doesn't heal. See a dermatologist for any spot that: Gets bigger or thicker Changes color Has an oddly shaped border Is bigger than a pencil eraser Crusts or scabs over and doesn't heal Swollen lymph nodes. Lumps in the side of your neck are most likely from strep throat or another infection. Less often, cancers like lymphoma or leukemia can make the lymph nodes swell up. Breast cancer that has spread can cause swelling in lymph nodes under the arms. If the swelling doesn't go away in a week or so, have your doctor take a look. Trouble swallowing. A feeling like there's a lump in your throat is a common symptom of heartburn. Less often, when you find it hard to swallow, it can signal cancer of the esophagus. If the feeling doesn't let up or it gets worse, see your doctor. Shed pounds without trying. As many as 2 of 5 people who are diagnosed with cancer have lost weight. There's no obvious cause. Get any unexplained weight loss checked out. Blood in urine or semen. A pink, brown, or red tinge to your pee or semen is usually nothing to panic over. Infections, kidney stones, injuries, and noncancerous prostate growth can all cause bleeding. Less often, bladder or prostate cancer might be to blame. Your doctor can do urine tests and other exams to find the source of the blood. Lump in the testicle. A painless one is a possible warning sign of testicular cancer. Yet the bump could also be from an injury, fluid buildup, or a hernia. It's hard to tell the cause from your symptoms alone, so go to your doctor for an exam. Pain during ejaculation or urination. If it hurts when you pee or have an orgasm, you may have an infection or swelling of your prostate gland or urethra. There's a chance that these symptoms might be because of prostate cancer. If the pain doesn't improve, have your doctor take a look. Breast lump or change. Although it's a hallmark symptom of breast cancer, most lumps aren't cancer. They're often fluid-filled cysts or noncancerous tumors. Still, see your doctor right away if you find any new or changing growths in your breasts, just to make sure. Also get these changes checked out: Redness or scaling of the skin over the breast Breast pain Nipple changes Lump under your arm Fluid that isn't breast milk leaking from the nipple Bleeding between periods or after menopause. Bleeding from the vagina during a woman's reproductive years is usually her monthly period. When it happens after menopause or outside of normal periods, cervical or endometrial cancer is a possibility. Call your doctor if you have any bleeding that's unusual for you.