Dear Doctor: Our daughter was successfully treated for leukemia as a child, but the chemotherapy she went through was pretty brutal. Now I've read that we have the first gene therapy for cancer, which is a huge deal. How does it work? How much does it cost? Are there side effects?

Dear Reader: We're so glad that your daughter's treatment was successful. As you mention, the therapies we currently rely on can take a steep physical toll. That's part of what makes new breakthroughs in precision medicine -- which includes targeted therapy, immunotherapy and gene therapy -- so promising and so exciting.

Before we get into the details of Kymriah, the name of the treatment you're writing about, it's important to note that gene therapy is still new and evolving. It's quite expensive, it doesn't help every person every time, and it can have side effects that range from challenging to life-threatening.

Kymriah is the first gene therapy to be approved by the Food and Drug Administration. It targets B-cell acute lymphoblastic leukemia, a cancer of the blood and bone marrow that affects children and young adults. The therapy, which received FDA approval in August 2017, was developed at the University of Pennsylvania, and is licensed by the drug company Novartis.

The therapy works by altering the genetic code within a patient's own T cells, which are part of the immune system. The T cells are extracted from the patient, frozen and then shipped to a Novartis lab in New Jersey. There, the patient's cells are reprogrammed to seek out and destroy the leukemia cells. They do this by targeting a specific protein that is unique to the leukemia cells.

When the rewired T cells are returned to the patient's body, they don't only attack the cancer, but they also multiply in number. According to the university's scientists, a single engineered cell can generate 10,000 new cells, and can survive in the body for years. This benefits patients with refractory leukemia, which is when leukemia cells persist in the body even after intensive treatment.

Side effects of Kymriah can be severe. It's possible that the altered T cells will set off a positive feedback loop within the immune system, known as a cytokine cascade. Symptoms include high fever, severe fatigue, rash, lung congestion, neurological issues and a dangerous drop in blood pressure. In some cases, these can lead to death. Because of this, Kymriah therapy may only take place at designated treatment centers, which are equipped to deal with these side effects.

Customizing each individual patient's cells is expensive. At this time, treatment with Kymriah runs about $475,000. Novartis has said it won't charge patients who don't respond to the drug within a month of treatment. Some types of financial aid are also available.

If turning your own cells into a successful cancer drug sounds hard to believe, you're not alone. When the first patient treated with Kymriah in 2010 was shown to be cancer-free a month later, even the lead scientists who developed the drug had trouble accepting it. They ordered a follow-up biopsy just to be sure.

Meanwhile, the research continues. The hope is that, with FDA approval of the first gene therapy, advancing and refining the science can move forward even more rapidly.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I'm a firefighter and in pretty good physical shape, even though I have Type 1 diabetes -- but my body doesn't show it. Specifically, I have flabby abs and man boobs. I walk, run, do push-ups and crunches, and I think I eat pretty well. What else can I do?

Dear Reader: First, I have some questions for you: How long has this been going on? Is the fat around the belly something new or something gradual over many years? Is the gynecomastia ("man boobs") something you have been dealing with since adolescence, or is it something you have only noticed recently?

Let us begin with gynecomastia. Gynecomastia occurs in adolescence due to a relative imbalance of estrogen and testosterone. The relatively elevated levels of estrogen compared to testosterone stimulate breast tissue in adolescent boys, leading to breast enlargement. The majority of adolescent boys will lose this breast tissue, but in 20 percent the enlarged breast tissue will persist into adulthood. In adult men, some estrogen is produced directly by the testes, but most is produced from the breakdown of testosterone and the adrenal hormone androstenedione. As in adolescent boys, adult men can develop gynecomastia if there is an imbalance between estrogen and testosterone levels.

Then, of course, there's obesity, which leads to increased fat in breast tissue. This can give the appearance of increased breast tissue, which is termed pseudo-gynecomastia. Because the fat in the breast tissue carries the enzyme that converts testosterone and androstenedione to estrogen, breast fat may actually increase estrogen levels and stimulate the formation of breast glands.

Because breast fat and the fat in your abdomen are related, the fundamental question is likely: Why are you storing fat?

First, blame the diabetes -- and the connection between the disease and your diet. As a Type 1 diabetic, you've probably been on insulin for many years. Insulin inhibits the breakdown of fat, but also stimulates the creation of fat. The higher your body's insulin level, the more your body will store fat. The more insulin you inject, the more fat you will store.

The higher your calorie intake and the higher your carbohydrate intake, the more insulin you will require to keep your blood sugar low. This will lead to a greater storage of fat. Look for foods that are low in glycemic index, meaning low in the food's ability to raise the blood sugar. Avoid high-sugar foods such as cookies, candies, cakes, sodas, ice cream and juices. These foods may no longer be part of your diet. But if they still are, and if your sincere desire is to remove the fat from your body, then eliminating these foods will help. I would also recommend limiting the amount of high-glycemic carbohydrates, such as bread, pasta, rice, corn and potatoes. Increasing fiber in your diet will also decrease your insulin requirements.

Then there's aerobic exercise. Walking, running, biking, rollerblading, hiking, swimming, using an elliptical machine -- all of these will help you lose and maintain a lower weight.

Of course, even with a good diet and exercise, you may have difficulty totally losing this unwanted fat. The important point is to be patient, diligent and more obsessive about your diet. This will decrease your insulin requirements, help control your diabetes and help you lose the fat.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: It seems like if you just wait long enough, everything about nutrition gets contradicted. So now fat is good, carbs are bad, and we don't really need more than 4 servings of vegetables a day? Really? Is everything we've been taught wrong?

Dear Reader: We hear this same frustration from many of our patients, and honestly, we're right there with you. Healthful eating is an important goal, but how are we supposed to achieve it if the rules keep changing?

When it comes to why nutrition advice keeps changing, several factors come into play: science, media and marketing.

Conclusions regarding diet and nutrition are frequently drawn from observational and epidemiological studies. Unlike in a clinical trial, where a single variable, such as a medication or a treatment approach, is scrutinized repeatedly in a randomized and rigidly controlled environment, observational and epidemiological studies draw conclusions by identifying and analyzing trends within large population groups.

Well-designed observational studies can provide valid results. But it's important to understand that the data they use include multiple variables that can't be controlled. Eggs and coffee are two culprit foods that have gone through the "it's bad"/"no, it's good" whiplash. Each of those foods was the focus as researchers combed through piles of data. However, the people in those studies were eating and drinking many more things. Add in variables like lifestyle and environment, and isolating the effect of eating any one specific food becomes challenging.

When researchers publish results that suggest a causal link between a certain food and a particular outcome, they acknowledge that it's just one single data point in an ongoing analysis. It takes time and repetition to reach a reliable conclusion. But scientific rigor pretty much flies out the window when it comes to how the emerging studies get publicized, which leads us to the second factor -- the media.

While scientists are saying, "In this one study, we see a link between eggs and heart disease," in the hands of over-eager newscasters, this is translated as "Eggs will kill you!" Meanwhile, time goes on. Many more studies are conducted. A decade or so later, armed with a wealth of data points collected over the years, the original thesis doesn't hold up. For the scientists, it's the nature of research -- precision and repetition over time. For the rest of us, it's a new -- and contradictory -- headline. "Eggs are good!"

Which brings us to marketing. Diet and nutrition are multibillion-dollar industries in the United States. That means that as food recommendations are crafted, a good bit of lobbying takes place. When new dietary guidelines were released in 2015, a number of nutrition experts, including Dr. David Heber, founding director of the Center for Human Nutrition at UCLA, bemoaned the influence of the food industry in the process.

We need to be savvy consumers of dietary information. And when it comes down to healthful eating, we recommend that our patients stick with the tried-and-true basics. That is, eat fish and lean meats, grains and legumes. Limit or cut out processed foods, and eat a wide variety of fruits and vegetables, especially leafy greens. Limit sugar and alcohol. When you're thirsty, reach for a glass of water.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)