Harvard Health Content API

Two forms of CPR are equally likely to save a life, two new studies conclude. And bystanders usually will help when they get firm, clear instructions, they found. One form of CPR uses a cycle of either 15 or 30 firm chest pushes and two quick breaths into the person’s mouth. The newer form is “hands-only.” It skips the breaths and uses 100 pushes per minute. The larger study included 1,900 people who saw someone in cardiac arrest and called 911. Dispatchers told them how to do a form of CPR. Half were randomly chosen to do each type. About 8 out of 10 were willing to try the hands-only form. About 7 out of 10 agreed to do the other form. Previous research has found that no more than one-third of bystanders will try CPR. Survival rates were about 12% for those who got either form of CPR. This is double the average survival for cardiac arrest outside a hospital.

Several tiny genetic differences can increase a woman’s risk of breast cancer, a study has found. Researchers tested the blood of 20,700 women. Half had breast cancer when the study began. The others did not. Researchers focused on the building blocks that form DNA. Sometimes one block is replaced by another. This is called a single-nucleotide polymorphism, or SNP. These often occur in the DNA between genes. Researchers found seven SNPs that had the biggest effect on breast cancer risk. Women were given a score based on how many of these they had. Women with the highest scores were twice as likely to have breast cancer as women with the lowest scores. The increase in risk was greatest for the most common type of breast cancer. This type grows in response to estrogen. The study appeared in the Journal of the American Medical Association. HealthDay News wrote about it July 27.

People should not let reports about the safety of certain chemicals deter them from using sunscreen, experts say. HealthDay News wrote about the topic July 26. The Environmental Working Group has raised questions about two chemicals. The group said that retinyl palmitate, which is related to vitamin A, increases the risk of skin cancer. Oxybenzone (benzophenone-3) disrupts hormones, the group said. Both chemicals are used in many sunscreens. But these concerns are unproven, dermatology experts told HealthDay News. Doubts are based mainly on studies of laboratory animals, they said. They emphasized that the threat of skin cancer from the sun is proven. People should use sunscreen and limit sun exposure, they said. The National Institutes of Health is reviewing data on retinyl palmitate. Results are due in January, HealthDay said.

People with high triglycerides are more likely to have specific variations in four genes, a study finds. Triglycerides are a type of fat in the blood. They are measured as part of the standard “cholesterol panel” of blood tests. Very high levels can make the blood pinkish, like cream of tomato soup. The new study looked at genes for 555 people with high triglycerides and 1,300 people with normal levels. People with high triglycerides were more likely to have common variations in four genes. They were also more likely to have rare variations in the same genes. Researchers said the gene combination may help to cause the condition. Research results were published in a letter to the journal Nature Genetics. The Vancouver Sun wrote about the study July 25.

People with very low levels of “bad” cholesterol (LDL) may not be helped by higher levels of “good” cholesterol (HDL), a study suggests. Researchers looked at both these types of blood fats in people who take powerful statin drugs. They used data from a study that gave rosuvastatin (Crestor) to people with average to low “bad” cholesterol. A similar group received placebo (fake) pills instead. Many people who received Crestor ended up with extremely low “bad” cholesterol. In the next five years, people who took Crestor had only half the heart attack and stroke rate as people who got the placebo pills. In this new study, researchers looked at “good” cholesterol levels for the same people. Among those who received Crestor, having a high level of “good” cholesterol made no difference in their heart attack or stroke risk.

Not every tear of a major knee ligament requires surgery, a new study concludes. The study focused on 121 active, young adults who had a tear in the anterior cruciate ligament (ACL). They were randomly divided into two groups. One group received surgery right away. This was followed by rehabilitation. The other group had rehab right away. They had surgery later if needed. Of 59 people assigned to rehab, 23 had the surgery later on. The other 36 did not need it. Two years after the injury, there was no difference in pain or function among the three groups — those who had surgery early, late or not at all. But every case is different, experts told HealthDay News. For instance, high-performing athletes probably would need surgery, they said. The study appeared July 22 in the New England Journal of Medicine.

Scientists are hailing a new vaginal gel as a breakthrough in the fight against HIV infection. Use of the gel cut in half a woman’s risk of being infected by a sex partner. The gel contains the drug tenofovir. This drug also is used to treat AIDS, the disease caused by HIV. The study included 889 heterosexual women in South Africa. They did not have HIV infection when the study started. Half of them were given the gel and told how to use it before and after sex. The other women received the same instructions, but a different gel. This gel was a placebo. It had no medicine in it. The researchers did not know which women got which gel. Neither did the women. After one year, the HIV infection rate in those who got the real drug was reduced by 50%, compared with women who got the placebo. After 2½ years, the rate was reduced by 39%. The journal Science published the study online.