Dear Doctor: I'm too old (almost 30) for the HPV vaccination that can reduce my risk of cervical cancer. But I read that an IUD could do the same thing. Should I think about getting one, even though I prefer other forms of contraception?

Dear Reader: What a good question -- and a relevant one. Cervical cancer is the third most-common cancer among women worldwide. The majority of cases and deaths occur in countries with poor access to regular Pap smears; in the United States, where Pap smears are more readily available, the rates of cervical cancer and cervical cancer deaths are dramatically lower. Vaccination against the human papilloma virus (HPV) -- the causative virus that leads to inflammation and eventually cancer of the cervix -- has the potential to reduce those rates even further, but the vaccine is given only to young people with no prior exposure to the virus.

The possibility of IUDs as a risk reducer is an intriguing notion that's been raised before. Intrauterine devices (IUDs) -- used in the United States since the late 1950s -- prevent sperm from joining with the egg by either damaging the sperm or creating a hostile environment for it. A 2011 study analyzed cervical cancer rates among women from 11 countries who had used an IUD and among women who hadn't. Women who had a history of IUD use had half the risk of developing cervical cancer as women with no IUD use, regardless of whether the use was for 10 years or only one year. There was no difference in HPV infection rates between the two groups, so obviously some other factor was involved.

The recent study you mention was a review of 16 studies exploring the link between cervical cancer and IUDs. The studies were from the 1980s and 1990s, and three of them were performed in the United States. Overall, cervical cancer rates were 30 percent lower among women using the device compared to nonusers. Keep in mind that the finding was a correlation and so does not prove that IUDs actually lower the rate of cervical cancer. But the authors surmised that the reason IUDs could potentially reduce the risk of cervical cancer is because insertion of an IUD causes an inflammatory reaction that increases the immune response in the cervix. This could lead to the clearance of the human papilloma virus.

The results of another study, one that followed 676 sexually active women in San Francisco from 2000 to 2014, conflict with this theory. The average age of the women at the beginning of the study was about 18. The women were routinely tested for HPV, and 85 of them used an IUD at some point during the study. No benefit was seen in either the acquisition or the clearance of HPV in women using an IUD. The authors of this study wondered if IUDs decreased the incidence of cervical cancer by somehow clearing precancerous lesions in the cervix.

In conclusion, I'm not certain that getting an IUD for the purpose of decreasing cervical cancer risk is necessary. It seems even less necessary if you have had multiple negative HPV tests and Pap smears. Nonetheless, for women making an initial birth control choice who are weighing the risks and benefits of an IUD, these studies may be an influencing factor.

(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.)

Welcome to part two of our discussion about high blood pressure. For those who missed it, a previous column examined new blood pressure guidelines released by the American Heart Association and the American College of Cardiology, in which normal is now a range below 120/80. It's a conservative definition that puts people with blood pressure in the range of 120-129/80 into the "elevated" category. This is not a diagnosis of high blood pressure, or hypertension. Rather, it's a warning sign that, without certain lifestyle changes, hypertension may well be in your future.

Now we'd like to expand on the techniques that can be helpful in getting better numbers.

-- Lose weight: Weight gain increases body mass, which means the heart has to pump harder to deliver blood throughout the body. At the same time, that increase in body mass offers greater resistance and results in elevated blood pressure. Studies show that a weight gain of even 5 pounds can cause blood pressure to rise.

-- Stop smoking: Not only do smokers face double the risk for stroke and heart attack as nonsmokers, they are also at increased risk of a range of cancers. In addition, the nicotine and other substances in cigarettes and other tobacco products make blood pressure go up.

-- Exercise regularly: Exercise strengthens the heart and makes it more efficient. Regular physical activity like brisk walks, cycling, swimming, dancing, hiking or active sports can lower your top (systolic) blood pressure number by four points. That's on par with what blood pressure medications will do. Aim for 150 minutes per week of moderate aerobic activity, or 75 minutes of vigorous activity.

-- Watch your diet: When it comes to food, the DASH diet (Dietary Approaches to Stop Hypertension) is a good guide. Not only does it naturally limit salt intake, but it also incorporates a healthful range of foods into your life. These include fresh fruits and vegetables, whole grains, legumes, nuts, lean proteins, limited saturated fats and limited amounts of sugar. You can get full details at: https://www.nhlbi.nih.gov/health-topics/dash-eating-plan.

-- Cut back on salt: New research suggests the relationship between salt and blood pressure is more complex than previously understood. Still, hidden salt in processed food means many Americans are getting far too much sodium. Switching to fresh foods and the rest of the DASH diet recommendations can make a difference.

-- Limit alcohol: Although we still don't know exactly how or why, drinking alcohol raises blood pressure. If you're a regular drinker, quitting can lower your top blood pressure number by several points.

-- Cut back on caffeine: As with alcohol, the mechanism behind the brief blood pressure spike that accompanies caffeine intake isn't fully understood. If you're looking to lower your blood pressure, though, we recommend cutting back on or quitting caffeine.

-- Reduce stress: Easier said than done, we know. But regular exercise, meditation, breathing exercises, yoga, a daily nap or just a bit of quiet time to yourself can help relieve tension.

-- Keep track: Make note of your blood pressure readings to track which direction you're trending. The American Heart Association supports self-monitoring, which can be done with a home blood pressure monitor and in partnership with your primary care physician.

(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 had problems with acid reflux for years -- until I started taking a proton pump inhibitor. Now I read they may raise the risk of stomach cancer. I don't want to go back to the days before my PPI, but I don't want cancer either. What should I do?

Dear Reader: I understand the life-changing potential of proton pump inhibitors (PPIs). These drugs are potent inhibitors of the acidity of the stomach. They help heal stomach ulcers, treat acid reflux and, in combination with antibiotics, combat Helicobacter pylori (H. pylori) infections. These infections increase the risk of stomach cancer, and eradicating the bacteria reduces the rate of cancer among those infected by 33 to 47 percent. Many people take the drugs long-term to decrease acid reflux and relieve stomach discomfort, so it's reasonable to question the safety of this, especially in light of the recent study.

But let's take a closer look at that study. It assessed the impact on 63,397 individuals successfully treated with drugs for H. pylori in Hong Kong, comparing those who then took a proton pump inhibitor to people who then didn't take any medication and to people who then took drugs known as histamine 2-blockers or H2 blockers, such as Zantac, Pepcid or Tagamet.

Participants were then followed for an average of 7.6 years, with 153 of them developing stomach cancer. Although this type of cancer is rare in the population, people who used PPIs at least once a week had a more than twofold risk of developing stomach cancer compared to the group using H2 blockers. Those who used PPIs daily had an eightfold risk of developing stomach cancer compared to the other group.

Length of use was linked to greater cancer risk as well. Thus, the study appeared to show a dose-dependent increase in the risk of gastric cancer. This correlation was specific to PPIs because H2 blockers did not show this increase.

But there are problems with this study. First, the average age of the PPI users was more than 10 years greater than that of the non-PPI users. Greater age itself is a risk factor for cancer. Second, participants in the group using PPIs were more likely to be obese, have diabetes, and be smokers or users of alcohol -- all of which are risk factors for gastric cancer. Of note, this study was in a mostly Asian population, which generally has a greater rate of gastric cancer.

Still, a 2017 Swedish study reached a similar conclusion. It looked at 797,067 people who consistently used PPIs, and researchers found that the rate of stomach cancer was three times greater in this population than in the general population. Again, this increased risk was not seen among people who used H2 blockers. But this study, too, was less than clear. Here, the rate of stomach cancer incrementally decreased such that people who took PPIs more than five years had a lower rate of stomach cancer than the general population.

In short, the data on PPI use and stomach cancer risk is not absolutely convincing. But I would still be wary of using proton pump inhibitors long-term, especially if you've been diagnosed with H. pylori infection. I'd recommend that you talk to your doctor about using an H2 blocker instead.

(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.)