Dear Doctor: How does prostate cancer happen? And what are the symptoms? I’m only 43, but I worry that I wouldn’t recognize the signs if I had it.

Dear Reader: Prostate cancer is one of the most common cancers among men in the United States. It occurs in the prostate gland, a male reproductive organ that sits between the penis and the rectum, just beneath the bladder. The prostate, which is about the size of a golf ball, wraps around the urethra, which is the duct through which urine and semen exit the body. One of the roles of the prostate is to produce fluids that nurture and support sperm, and to propel these fluids into the urethra when needed.

When normal cell division goes awry, the chaotic and uncontrolled growth that results is what we know as cancer. In prostate cancer, the rogue cells use hormones known as androgens, which include testosterone, to fuel their growth. Although prostate cancers begin within the gland, they can spread to nearby regions of the body, including the lymph nodes. Some prostate cancers are slow to grow and can take years to be detected. When slow-growing cancers are identified, the risk they pose may be low enough that physicians recommend careful monitoring, often referred to as "watchful waiting." Other prostate cancers are more aggressive and require swift treatment.

The American Cancer Society estimates that more than 174,650 new cases of prostate cancer will be diagnosed this year, and the disease will claim more than 31,000 lives. As you allude to when mentioning your age, the majority of prostate cancers -- about 60 percent -- are diagnosed in men 65 and older. But race plays a role as well. Prostate cancer affects black men at two to three times the rate of white men and at an earlier age. They are also more likely to die from the disease.

Although a screening tool known as a prostate-specific antigen (PSA) test is effective at detecting certain hormonal changes associated with prostate cancer, it has been overused in the past and led to unnecessary treatment. The U.S. Preventive Task Force recommends that for men between the ages of 55 to 69, prostate cancer screening should be a decision made by patients and doctors working together on a case-by-case basis. However, a survey of prostate cancer outcomes by several colleagues at UCLA determined that, due to their elevated risk, black men would benefit from prostate cancer screening guidelines tailored to their unique and specific needs.

When it comes to symptoms, unfortunately prostate cancer is often largely silent in the early stages. As the cancer becomes more advanced and affects the size and shape of the prostate, the gland’s position in the body may lead to symptoms that include:

-- Difficulty urinating.

-- Frequent urination.

-- A diminished stream of urine.

-- Pelvic discomfort.

-- Signs of blood in the semen.

-- Onset of difficulty achieving or maintaining an erection.

-- Discomfort when sitting.

If you develop these symptoms, please talk to your doctor. It doesn’t mean that you have cancer, but you will be taking the first step to finding out what, if anything, may be wrong.

(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’m a 38-year-old man, and because I live in a loud environment, I’ve used soft foam earplugs at night for the past three years. Are they safe to wear for extended periods of time? I’ve lost half the hearing in my right ear and wonder if it could be from wearing earplugs for so long.

Dear Reader: Sleeping in a noisy environment is not only a challenge, but it also affects the quality of the sleep that you manage to get. Sleep is a complex process with multiple stages, each of them equally important. Not only does uninterrupted sleep help you feel rested, but research has shown the quality of the sleep we get affects our physical and mental health as well. A report issued by the Institute of Medicine Committee on Sleep Medicine and Research found that the length and quality of sleep played a role in a wide range of conditions, including hypertension, diabetes, depression, obesity and cardiovascular disease.

Earplugs can be an effective way to deal with a variety of sounds that interrupt sleep. They form a seal around the entrance to the ear canal and physically block the vibrations that would otherwise reach the eardrum and get sent to the brain to be interpreted as sound. Unfortunately, when earplugs are used incorrectly, they can lead to damage to the ears or to hearing.

One of those risks is related to earwax, a waxy oil known as cerumen. It’s produced by glands in our ears and naturally finds its way into and out of the ear canal over the course of the day and night. Earwax protects the skin within the ear canal, has a role in cleaning and lubrication, and serves as a protective barrier against moisture, dust, bacteria, fungi and other unwelcome substances. Long-term use of earplugs can interfere with the self-cleaning flow of earwax; rather than letting it drain, it can result in a buildup. This can lead to tinnitus, which is ringing in the ears, or even to hearing loss. A health care professional can use a device known as an otoscope to look deep into the ear to check whether the ear canal is blocked. He or she will then remove the excess earwax by first softening it with warm water or a special solution, followed by gentle manual extraction.

Another potential risk is infection due to bacterial buildup on the earplug’s surface, which then gets transferred into the ear canal. This can occur when the same pair of earplugs is used repeatedly and can lead to hearing loss. The best way to avoid problems is to be vigilant about practicing earplug hygiene. Pre-molded earplugs, which are reusable, must be cleaned daily. Foam earplugs should be discarded regularly -- daily if at all possible. It’s important to store any earplugs in a ventilated case to prevent bacterial buildup due to moisture.

Reusable earplugs can be uncomfortable for sleeping, and disposables may not be in everyone’s budget. In those cases, consider over-the-ear protection, like noise-canceling ear muffs, which reduce sound without touching the ear canal.

(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: Unless I’m cooking, my boyfriend eats only junk food and fast food. He says it’s no big deal because he’s not overweight and doesn’t have high cholesterol or high blood pressure. Is he right?

Dear Reader: There’s something important missing in your boyfriend’s theory regarding his less-than-stellar eating habits, and that’s the word “yet.” He isn’t overweight and he doesn’t have high cholesterol or high blood pressure -- yet. But decades of research point to the hard truth that a diet that regularly includes what we refer to as junk food is associated with a wide range of unhealthful and even dangerous consequences.

A survey of this research published a few years ago found that eating fast food more than twice a week increased the risk of high cholesterol and high blood pressure, which top the list of risk factors for cardiovascular disease, heart attack and stroke. It also paved the way for insulin resistance, diabetes, certain cancers, intestinal issues, an increased incidence of obesity and even depression.

Scientists in France recently looked at how a diet of junk food and fast food (the researchers refer to these as "ultraprocessed foods") may affect a person’s life span. The study, published in February in the journal JAMA Internal Medicine, examined eight years of dietary data collected from middle-aged volunteers in an ongoing nutritional study in France. Among the findings was a correlation between early death and regularly eating ultraprocessed foods. New information is also emerging about the negative effect of these foods on the gut microbiome, including reducing the numbers and diversity of beneficial bacteria.

So what are ultraprocessed foods? They’re premade and prepackaged foods whose original ingredients have been transformed with flavorings, additives and preservatives. Quite often, ultraprocessed foods achieve their final form via industrial methods like extrusion, molding and milling. The end result is that they’re flavor bombs that are high in salt, fat, sugar and calories, and low on fiber and nutrients. Not only are these foods inexpensive and readily available, the balance of salt, sugar, fat and added flavorings has been purposely engineered by food scientists to be irresistible. There’s even a term for it -- the "bliss point." Small wonder that the bag of cheese puffs or side of french fries is so easy to crave and so hard to put down.

Research shows that the potential ill effects of this type of eating reach the brain as well. Not only are the connections between the neurons in our brains adversely affected by unhealthy diets, so are several molecules related to learning and memory.

All of which brings us back to our original point. If your boyfriend doesn’t shift to healthier eating, it’s just a matter of time before his body begins to pay the price. But he doesn’t have to go cold turkey. When it comes to sweets and "treat" foods, we generally advise our patients to limit them to 20 percent of their total intake. For those with health issues such as hypertension or diabetes, we advise limiting splurges to 10 percent. Change can be hard. If he approaches healthy eating gradually but steadily, it will be easier to succeed.

(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.)