Dear Doctor: I’m old enough to remember the shock over actress Farrah Fawcett’s anal cancer diagnosis, which was not a disease you heard much about. Now I’m reading that this type of cancer is relatively common. Isn’t there some kind of screening test?

Dear Reader: It’s true that Farrah Fawcett made international news when she went public with her diagnosis of anal cancer in 2006. Due to taboos associated with its location in the body, anal cancer was seldom discussed. The actress made a point of publicly sharing her medical journey until her death three years later, and she was applauded for helping to ease the stigma associated with the disease.

Now, with the release of findings from a new study, anal cancer is in the spotlight once again. According to the study, which looked at data collected by U.S. cancer registries between 2001 and 2015, the incidence of the most common type of anal cancer rose 2.7% each year for the last 15 years. The researchers said this annual increase makes anal cancer one of the fastest-growing cancer diagnoses in the U.S., particularly among young black men and older women. The reason for this increase is not yet clear.

The public silence around anal cancer means that most people know very little about the disease. It’s a relatively rare form of cancer, with about 8,300 new cases diagnosed each year. The disease is about twice as common in women as in men, and it occurs most often in people over age 50. Many are surprised to learn that the majority of cases -- more than 90% -- are caused by the human papilloma virus, or HPV. This is the same virus that we now know causes most cervical cancers, as well as many cancers of the penis, vagina and vulva. However, it is important to note that only a small fraction of those infected with HPV go on to develop cancer -- in fact, there are more than 100 strains of the virus, but many are considered “low-risk.”

Anal cancer occurs when abnormal cells begin to grow in the anal canal, the final segment of the large intestine. Symptoms of anal cancer include bleeding, stool mixed with visible blood, pain, the presence of a mass or growth, and more rarely, persistent itching. Several of these symptoms match symptoms of hemorrhoids. Hemorrhoids can usually be diagnosed with a visual and rectal exam. Anal cancer is diagnosed via a biopsy. In addition to age, race, gender and infection with HPV, risk factors for anal cancer include a history of smoking, anal sex with younger male partners, chronic inflammation and suppressed immunity due to disease or medical treatment.

Although there are no screening guidelines for anal cancer at this time, individuals who are at risk can talk to their doctors about tests or procedures. These include rectal exams and anal Pap tests. The HPV vaccine, which is recommended for both female and male adolescents, may also be helpful for adults in certain cases.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I just turned 65, and my doctor wants me to have a bone density test. What is it, and how does it work?

Dear Reader: A bone mineral density test, or BMD, measures the strength of one’s bones. It’s an important diagnostic tool for osteoporosis, a progressive disease in which bones become brittle and fragile and can easily break.

Although our bones appear hard and static, they are made up of living tissue. The honeycombed inner framework of a bone is composed of collagen, which is a protein. A mineral known as calcium phosphate provides strength and solidity. Together, these two substances create a strong and flexible structure that successfully withstands stress.

Our skeletons have a dynamic life cycle in which old bone is continuously removed, while at the same time new bone is added. In children and teens, the addition part of the cycle outpaces removal, allowing the skeletal bones to grow in both strength and density. This cycle peaks sometime in our late 20s, at which point bone reabsorption gradually begins to overtake bone formation. Certain hormonal changes that occur in women during menopause further accelerate that imbalance. The result is that old bone may be removed too quickly, new bone may be added too slowly, or both. Over time, the honeycomb framework within the bone grows increasingly porous, while the exterior structure becomes thinner.

All of this leads us back to the scan your doctor has recommended. Known as a DXA test -- that’s short for dual-energy X-ray absorptiometry -- it’s essentially the same procedure and technology used in a standard X-ray. A machine delivers low-dose X-rays, which measure the amount of calcium and other bone minerals present in a segment of bone. The proportion of bone minerals to soft tissue reveals bone density.

The DXA test, which is most often used to measure bone density at the hip and the lumbar spine, is used to diagnose osteoporosis. It can also help assess risk of future fractures, and to detect whether a treatment for osteoporosis is working. The test, which is as quick and painless as an X-ray, is performed on an outpatient basis. It takes from 15 to 30 minutes to complete, depending on the part of the body being scanned. The results of the test, known as a T score, are presented as a comparison between your own bone density and that of a young adult at the peak of bone formation. A second measurement, known as a Z score, compares your bone density to people your own age, size and gender.

The BMD test is usually recommended for women when they turn 65. It may be recommended earlier than that if a woman has rheumatoid arthritis, low body weight or low vitamin D levels; has used a corticosteroid for three or more months; has a family history of osteoporosis; has experienced bone breaks resulting from a minor accident; has lost height; or is a heavy smoker or drinker. Depending on the results of the initial test, a followup test may be needed in one or two years.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: My wife overindulged on her birthday and wound up with a pretty fierce hangover -- headache, nausea, brain fog, the works. She got so much weird advice that it got us to wondering, what exactly is a hangover? Are there any remedies that actually work?

Dear Reader: Your question is one for the ages -- literally. References to the unique state of distress we call a hangover date back thousands of years. So does the quest for a cure. Yet despite the best efforts of modern science, the cause of a hangover -- as well as a remedy -- remains unclear.

Let’s start with what we do know. A hangover occurs when you drink too much alcohol. For some, a few glasses of wine can lead to profound regret the morning after. For others, getting a hangover takes a night of excessive drinking of hard liquor. No matter the amount of alcohol, the symptoms remain the same. These include the headache, nausea and cognitive issues that your wife suffered from, as well as dry mouth, thirst, fatigue, dizziness, vertigo, diarrhea, tremors, disturbed sleep, rapid heartbeat, excessive perspiration, anxiety, low mood and sensitivity to light and sound.

Research suggests that genetics play a role in how much you can drink before you’ve earned yourself a hangover. So do a person’s age, sex and physical health; the state of their immune system; and how quickly they drink. The specific type of alcohol may also be a factor. Darker-colored drinks -- such as bourbon, dark beer and red wine -- contain higher concentrations of compounds known as congeners. The body metabolizes these into toxic substances such as formaldehyde and formic acid, which can add to hangover misery.

Dehydration was long considered a prime culprit in hangover symptoms, but recent research has found no difference in electrolyte levels among people who are hung over and those who are not. Although a toxic compound known as acetaldehyde, produced when the body breaks down ethanol, had been implicated in hangover misery, more recent research now points to the role of cytokines. These are small proteins associated with inflammation, which the immune system uses for signaling. The theory is that drinking triggers the release of cytokines, which in turn unleash the full fury of the immune system.

As for how to cure a hangover, science hasn’t gotten that far. The best you can do is manage the symptoms for the eight to 24 hours it takes for a hangover to play out. First, skip hair-of-the-dog therapy. More alcohol may give a temporary boost, but soon enough leads to the throes of even more misery. Instead, drink plenty of water, eat complex carbs to boost low blood sugar and fend off nausea, use antacids if needed for stomach upset, and get some sleep. Aspirin and other non-steroidal anti-inflammatories can help with headache, but can also irritate the stomach. Never take Tylenol during or right after drinking, as it can cause liver damage when mixed with alcohol. No one who has ever had a hangover wants to hear this, but the only certain cure is time.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)