Four months before the November election, Republican Sen. John McCain found a strange mole during a regular skin-cancer screening.

A doctor removed the spot and, on July 29, reported that the presumptive Republican nominee for president was fine. No cancer was found this time. But on three previous occasions, McCain's mole biopsies have turned up melanoma.

"If you ever have any slight discoloration, please go to your dermatologist or your doctor and get it checked out as soon as possible," McCain said, as reported by the Associated Press.

Skin-cancer checks are just one of the big three screenings you can and should do at home, experts say.

Follow McCain's Advice

Skin cancer is curable when caught early, so make a habit of checking yourself. People of all ages need to get in a regular habit of looking over every inch of their skin and noting the color and size of existing moles or discolorations.

Doctors said twice-annual checks will be enough to detect changes, but some people forget to do them.

"You’ll want to do it monthly. Less frequent(ly), and you’ll forget to do it," said Dr. Chad Vokoun, assistant professor in the Department of Internal Medicine at the University of Nebraska Medical Center. "Six months would be OK, but you forget."

So either write it on a calendar or pick a day each month to screen yourself.

Some of the skin most prone to cancer, because it's in the sunlight most, is the back of neck and behind the ears.

"Have a good mirror or a good friend or partner able to check your back," said Kathy Christiansen, the program manager for the Cancer Prevention and Hereditary Cancer Risk Program at Omaha's Methodist Hospital. "Look for any skin blemish that is not normal for you."

That's the key to screening for cancer -- recognize what's normal and note what's not.

Use the alphabet of skin cancer to help you decide whether to see a doctor. A is for asymmetry, where one half of a mole or blemish looks different than the other half. B is for border irregularity. C is for color -- you're looking for one part of the blemish to be darker or redder. D is for diameter, and a mole bigger than a pencil eraser may be a problem. See photos and learn more about skin self-exams at the American Academy of Dermatology's Web site.

Check Your Breasts

Women need to get into the habit of monthly breast self-examinations. The best way to do it, doctors said, is in the shower and five days after a period.

"Use your first three fingers and go in a circular motion from the nipple around. It doesn't matter how you do it -- just be consistent," Christiansen said. "You can also do up and down and up and down. (Then) look in the mirror. Sometimes the nipple might retract (or) you could see dimpling. There's one cancer -- inflammatory breast cancer -- that can show up like a rash. Check under armpits with the pads of your fingers for lymph checks."

Vokoun said every woman's breasts have lumps. Again, the key is to recognize what's normal for you and note changes.

Also note that menstruation changes breast tissue, so women should not test during their periods, as they may set off alarm bells unnecessarily.

Testicular Cancer Threatens Young Men

The average ages for testicular cancer diagnoses are 15 to 35, statistics show. At least a couple of times a year, men of all ages -- but especially young men -- need to use their fingers to check for lumps.

"This is a young person’s disease," Vokoun said. "That’s an uncomfortable thing to do those self-exams. You’re just starting to know your body. But a good place is the shower, and probably monthly (to make the habit). Pain is rarely a symptom. It’s usually just a lump."

Vokoun said a lump will usually only be found on one side or the other. He said the good news -- and the incentive to do the self-exams -- is that testicular cancer is one of the only 100 percent curable cancers, if caught early.

When Should I See A Doctor?

For any of the three major cancer self-exams, the time to see a doctor is when you note a change. Doctors said the first call should be to your family doctor or primary care physician. That person will decide how comfortable they are with diagnosing themselves or refer you to a specialist.

People with potential skin cancer cases should expect to have a biopsy performed on part of the blemish. Breast and testicular cancer screenings may start with an MRI or ultrasound before the procedure gets more invasive.

Don't wait if you note a change.

"Screening of these sorts are a part of the larger picture of a healthy lifestyle," said Creighton University Medical Center's Dr. Donald Frey, the chair of Department of Family Medicine. "Unless we view screening in the context of prevention and diet and exercise, then the screening opens a conversation. When screening results are viewed in context of the big picture, it’s more helpful."

Women should get their first annual mammogram at age 40, doctors advise. White men need prostate screenings starting at age 50. Black men should start at 40. Both men and women need some kind of colon screening at age 50, doctors said. In all cases, a family history of cancer may move up annual doctor's office screenings to younger ages.

Other At-Home Tests

Frey said at-home pregnancy tests have advanced so far in the past few years that there is little difference in the accuracy of an at-home test done correctly and a clinical test. He said at-home testers should hold a great deal of confidence in the results.

On the other hand, blood-sugar test kits are great for diabetics who need to screen several times a day to control insulin. But Frey said some people interested in their blood-sugar readings are using the at-home tests improperly. He said that without guidance from a physician, knowing your sugar reading is a waste of money and may cause undue worry.

"See a doctor for blood testing so you’ll get ideas about what to do with the results," Frey said.