Dear Doctor: I started smoking when I was 25 and stopped when I was 40. I‘m 56 now, and because I was a heavy smoker, I’m really worried about the damage I may have done. Do you think I can get scanned just to be sure everything is OK? Would my insurance pay for it?

Dear Reader: You are not alone in seeking reassurance about the effects of your former smoking habit. Both the federal government and private insurers agree that in cases like yours, lung cancer screenings may be useful.

Research published in the New England Journal of Medicine in 2011 found that when current and former heavy smokers underwent low-dose CT scans, which are a type of X-ray, to screen for cancer and for suspicious changes to lung tissues, a significant number of cancers were caught at an early stage. Researchers reported that the outcome of these screenings was a 20 percent reduction in lung cancer deaths among the population studied. That led to the current recommendation that adults between the ages of 55 and 80 who have smoked 30 packs of cigarettes per year within the last 15 years should undergo a scan. This recommendation covers current smokers and those who have quit within the last 15 years.

Lung cancer is the leading cause of cancer death in the United States, with smoking contributing to up to 90 percent of those deaths among both men and women. According to the American Lung Association, women who smoke are 13 times more likely than nonsmokers to go on to develop lung cancer. Among men, that likelihood goes up to 23 times the rate of nonsmokers. When people who don’t smoke are regularly exposed to secondhand smoke either at home or at work, their risk of developing lung cancer rises 20 to 30 percent. And as long as we’re on the topic, cigarette smoking accounts for about 20 percent of all deaths from heart disease in the U.S. All of which is leading us to our ongoing plea in these columns -- if you’re a smoker, please stop. If you’re not, please don’t be tempted to start.

When it comes to the lung cancer screening recommendations, though, it’s important to note that it’s actually a complex issue. On the plus side is the fact that cancers caught early are easier to treat. However, screening includes the risk of a false-positive result. That’s when a test seems to identify disease when no disease is present. Also of concern is something known as over-diagnosis, which is the discovery of cancer that would not have caused problems to the patient. Each of these can lead to unnecessary procedures and treatment. That’s why screenings are recommended only for heavy smokers and only within a set time frame.

For those who do get a positive result from a screening, it’s important to talk to your health care team about follow-up screenings. Our recommendation is to talk all of this over with your family doctor before you make any decisions regarding a lung cancer screening.

(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 saw on TV that someone who’s allergic to fish actually died just from smelling it. Is that really possible?

Dear Reader: You’re referring to a news story about an 11-year-old boy who died on New Year’s Day after visiting relatives in whose home fish was cooking. The boy, who was allergic to both seafood and peanuts, did not eat or touch the fish. When he told his parents he felt ill and was having trouble breathing, they treated him with the nebulizer he carried because he also suffered from asthma. At first the treatment appeared to be successful. Soon, however, the boy’s condition worsened and paramedics were called. The boy, who became unconscious and unresponsive, was transported to a local hospital where he was pronounced dead.

The circumstances were so unusual that a definitive cause of death was not immediately announced, and the case was referred to the medical examiner’s office. However, authorities believe that vapors from the cooking process contained fish proteins, which activated the child’s immune system when he inhaled them. This triggered an allergic response, which, in combination with his asthma, proved to be fatal.

A food allergy is a chronic overreaction by the immune system to even a minute amount of a specific food. The most common allergies are to the proteins found in peanuts, tree nuts, cow’s milk, fish and shellfish, eggs, wheat and soy. Although these proteins are not actually dangerous, the immune system of an allergic person will flag them as a threat. It will then mount an attack that produces physical symptoms that range from mild to dangerous. These include digestive problems, tingling, itching, rash, flushing, hives and swelling of the lips, tongue, face, throat or other parts of the body.

The most severe allergic reaction is anaphylaxis, which is life-threatening. When this occurs, the airways can become so swollen it becomes difficult or impossible to breathe. Other symptoms of anaphylaxis include rapid pulse, loss of consciousness and a severe drop in blood pressure. Immediate medical treatment for anaphylaxis is crucial. Reaction to a food allergen begins anywhere from several minutes to several hours after eating the trigger food.

It’s estimated that of the 15 million Americans with food allergies, about 6 million are children younger than 18. Close to one-third of those are allergic to more than one food. Although it is not known why, food allergies are on the rise. Between 1997 and 2008, peanut and tree nut allergies in children tripled. All-cause food allergies in children increased by 50 percent between 1997 and 2011. Not only does this result in tens of thousands of health emergencies in children each year, there’s a financial cost as well. It’s estimated that families spend upwards of $25 billion annually caring for children with food allergies. Recent spikes in the cost of epinephrine auto-injectors have angered families and health professionals alike and made headline news.

Although the hypersensitivity in this case is rare, it is becoming an increasingly recognized problem. The American College of Allergy, Asthma and Immunology warns anyone with a fish or seafood allergy to avoid any area where these foods are being cooked.

(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: Help! I just saw on TV that half of all Americans now have heart disease. How did this happen? How do I know if I'm one of the 50 percent?

Dear Reader: You're referring to a new report from the American Heart Association, which was published at the start of this year. The statistical update concluded that at least 48 percent of American adults have some sort of cardiovascular disease. Individuals under the age of 18 were not included in the report, so it's not actually half of all Americans. The update, which is released at the start of each new year, is compiled in collaboration with a number of government agencies, including the National Institutes of Health.

To understand why this number is suddenly so high, we need to rewind to 2017. That's when the joint American Heart Association-American College of Cardiology hypertension guidelines got an update. At that time, the definition of high blood pressure was lowered from 140/90 mm Hg to 130/80 mm Hg. In one fell swoop, millions of Americans who thought they had normal blood pressure the day before were suddenly in the hypertensive category.

Some of you may remember that this change to the definition of high blood pressure proved to be controversial. The lower benchmark was based on a medical trial in which the method of measuring blood pressure was markedly different from what you'll typically undergo in a medical setting. Participants were allowed to sit quietly for several minutes before an automated device was used to measure their blood pressure. The final reading was derived from the average of up to three separate measurements. This all led to some robust debate in the medical community.

Another factor in the new heart disease estimates is the definition of cardiovascular disease itself. It includes heart failure, stroke, coronary heart disease, and yes, high blood pressure. That means anyone with a blood pressure reading of 130/80 mm Hg or higher now meets the definition of heart disease. But when you exclude high blood pressure and focus solely on the other three conditions, the prevalence of cardiovascular disease among American adults drops to 9 percent overall.

Still, high blood pressure is dangerous. Not only is it the most common risk factor for stroke and heart disease, it plays a role in a number of other serious health conditions. The challenge is that high blood pressure is a silent condition. You can't feel it. But inside the body, all sorts of bad things are happening. Over time, uncontrolled high blood pressure can damage and weaken arteries, the heart and blood vessels in the brain. The blood vessels in the eyes and kidneys are also at risk. Research continues to show a connection between high blood pressure and certain types of cognitive impairment and dementia. That's why, through lifestyle changes, medication or both, controlling blood pressure is important to good health.

As for learning about the status of your own heart health, the best way is to see your primary care physician. Through a physical examination and certain tests, including a blood pressure reading and a lipid profile, you'll learn where you stand.

(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.)