Archives November 2023

When cancer patients are treated with radiation, it’s possible that the therapy itself may cause new tumors to form in the body later. Radiation kills cancer cells by damaging their DNA, but if the treatments cause genetic damage to normal cells near the radiation target, there’s a small risk that these secondary malignancies may arise over time.

Just over 10 years ago, Canadian researchers set out to assess the risk of secondary malignancy among men with prostate cancer who were treated with a type of radiation called brachytherapy. Unlike radiation delivered from sources outside the body, brachytherapy is accomplished by implanting dozens of radioactive pellets, or “seeds,” directly into the tumor site. Those seeds, which are never removed, emit radiation at a dose that declines toward zero over the course of a year.

Brachytherapy has the advantage of convenience. Instead of traveling for repeat sessions of radiation, men need only one treatment, usually given in an outpatient setting. But brachytherapy is also falling out of favor, in part because newer types of external beam radiation deliver high-precision doses with fewer side effects.

Study methodology and results

The Canadian study compared rates of secondary malignancies in the pelvis among men treated either with brachytherapy or with surgery to remove the prostate. All the treatments took place in British Columbia between 1998 and 2000. The brachytherapy group included 2,418 men with an average age of 66, while the surgically-treated group contained 4,015 men whose average age was 62. Within that group, 2,643 men had been treated with surgery alone, and 1,372 men with surgery plus external beam radiation given later.

After median follow-ups of between 5.8 years (brachytherapy) and 6.4 years (surgery), the study team reported in 2014 that there was no difference in rates of secondary malignancies between the groups, or with cancer incidence in the general population.

But that’s no longer the case: In April 2024, the researchers published updated findings. This time, rates of new cancers in the pelvis — including the bladder and rectum — were higher in the brachytherapy group. Specifically, 6.4% of brachytherapy-treated men had secondary malignancies at 15 years of follow-up, increasing to 9.8% after 20 years. By contrast, 3.2% and 4.2% of surgically-treated men developed secondary pelvic malignancies over the same durations. There was no difference in deaths from secondary malignancies between the groups.

The strength of the association with bladder cancer in particular is “similar to that seen with smoking,” wrote the author of an accompanying editorial. Results from the study “should be considered when treating men with localized prostate cancer who have a long life expectancy,” the authors concluded.

Commentary from experts

“I do believe that this study reveals a dark truth about radiation for prostate cancer that has been long suspected,” says Dr. Anthony Zietman, a professor of radiation oncology at Harvard Medical School and Massachusetts General Hospital, and a member of the advisory and editorial board for the Harvard Medical School Guide to Prostate Diseases. “As the decades pass after radiation therapy of any kind — brachytherapy or external beam — the risk for radiation-induced malignancies rises.

“These malignancies are usually in adjacent organs like the bladder and rectum, or within the prostate itself. They may be very curable, and thus the survival rates are the same for radiation or surgically treated patients, but there is little doubt that, for these patients, they represent a ‘sting in the tail’ long after the radiation has been given and forgotten. This data certainly gives us pause when offering radiation to very young men with several decades of life expectancy ahead of them, and it also reminds us of the value of follow-up visits.”

“The fact that second cancers arise in the area where radiation was given is not surprising, but the magnitude of the long-term increases is concerning,” added Dr. Marc Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor in chief of the Harvard Medical School Guide to Prostate Diseases. “There are other common and troublesome urinary side effects of brachytherapy — independent of second cancers — that patients should fully consider before selecting it as a treatment option. This is especially true given the availability of other convenient and similarly effective prostate cancer therapies.”

About the Author

Charlie Schmidt, Editor, Harvard Medical School Annual Report on Prostate Diseases

Charlie Schmidt is an award-winning freelance science writer based in Portland, Maine. In addition to writing for Harvard Health Publishing, Charlie has written for Science magazine, the Journal of the National Cancer Institute, Environmental Health Perspectives, … See Full Bio View all posts by Charlie Schmidt

About the Reviewer

Marc B. Garnick, MD, Editor in Chief, Harvard Medical School Annual Report on Prostate Diseases; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Marc B. Garnick is an internationally renowned expert in medical oncology and urologic cancer. A clinical professor of medicine at Harvard Medical School, he also maintains an active clinical practice at Beth Israel Deaconess Medical … See Full Bio View all posts by Marc B. Garnick, MD

Picture this: you’re with friends in an unfamiliar forest using only a map and a compass to guide you to an upcoming checkpoint. There are no cell phones or GPS gadgets to help, just good old brainpower fueled by a sense of adventure as you wind through leafy trees and dappled sunlight.

This is not an excursion to a campsite or a treasure hunt. It’s a navigation sport called orienteering — a fun way to get outside, exercise, and maybe even help fight cognitive decline, according to a 2023 study.

What is orienteering?

Orienteering combines map and compass reading with exercise. Competitors (“orienteers”) race against a clock to reach checkpoints in outdoor settings that can range from city parks to remote areas with mountains, lakes, rivers, or snowy fields.

“You can go out in a group or on your own. You get a very detailed map and navigate your way to checkpoints that record your time electronically,” says Clinton Morse, national communications manager with Orienteering USA, the national governing body for the sport in the United States.

Because orienteers are racing the clock, they might run on trails, hike up hills, or scramble around boulders. That’s for foot-orienteering events. There are also orienteering events with courses geared for mountain biking, cross-country skiing, or canoeing.

How might orienteering affect thinking skills?

A small 2023 study published online in PLoS One found a potential link between orienteering and sharp thinking skills.

Researchers asked 158 healthy people, ages 18 to 87, about their health, activities, navigation abilities, and memory. About half of the participants had varying levels of orienteering experience. The other participants were physically active but weren’t orienteers.

Compared with study participants who didn’t engage in orienteering, those who were orienteers reported

• having better navigational processing skills (recognizing where objects were, and where participants were in relation to the objects)
• having better navigational memory skills (recalling routes and landmarks).

The study was observational — that is, not a true experiment — and thus didn’t prove that orienteering boosted people’s thinking skills. But the link might be plausible.

“Aerobic exercise releases chemicals in the brain that foster the growth of new brain cells. And when you use a map and connect it to landmarks, you stimulate growth between brain cells,” says Dr. Andrew Budson, lecturer in neurology at Harvard Medical School and chief of cognitive and behavioral neurology at VA Boston Healthcare System.

Where can you find orienteering opportunities?

There are about 70 orienteering clubs across the United States, and many more around the world (the sport is extremely popular in Europe). To find an orienteering event in your area, use the club finder tool offered by Orienteering USA.

How can you get started with orienteering?

People of all ages and athletic levels can take part, because orienteering courses vary from local parks to wilderness experiences. Costs are about $7 to $10 per person for local events, or $25 to $40 per person for national events, plus any travel and lodging expenses.

To make orienteering easy at first, Morse suggests going with a group and taking things slowly on a short novice course. “You don’t have to race,” he says. “Some people do this recreationally to enjoy the challenge of completing a course at their own pace.”

The trickiest part is learning to read the map. Morse’s advice:

• Turn the map as you change directions. Hold the map so that the direction you’re heading in is at the top of the page. For example, if the compass indicates that you’re heading south, turn the map upside down, so the south part is on top and easier to follow.
• Create a mental image of what the map is telling you. If there’s a fence along a field on the map, build a picture of it in your mind so you can recognize it when you see it, even if you haven’t been there before.

Tips for safe and enjoyable orienteering events:

• Dress appropriately. Wear comfortable clothes including long pants, good walking shoes, and a hat.
• Lather up. You’ll be outside for at least an hour, and you’ll need sunblock and possibly tick and bug spray depending on the terrain. Preventing tick bites that can lead to Lyme disease and other tick-borne illnesses is important in many locations.
• Bring some essentials. Pack water, a snack, sunblock, bug spray, and your phone. (Keep the phone turned off unless you need to call for help.)
• Use good judgment. Know that the shortest route on the map won’t always be the best, since it might take you up a hill or through thick vegetation. It might be better to go around those areas.

Once you learn the basics of orienteering, you can make it more physically challenging (and a better workout) by going faster and trying to beat your previous times, or by signing up for a more advanced course that’s longer and requires more exertion and speed.

And no matter which event you take part in, enjoy the adventure. “You’re not just following a path, you’re solving puzzles while being immersed in nature,” Morse says. “It’s a great way to experience the outdoors.”

About the Author

Heidi Godman, Executive Editor, Harvard Health Letter

Heidi Godman is the executive editor of the Harvard Health Letter. Before coming to the Health Letter, she was an award-winning television news anchor and medical reporter for 25 years. Heidi was named a journalism fellow … See Full Bio View all posts by Heidi Godman

About the Reviewer

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio View all posts by Howard E. LeWine, MD

If you spend time outdoors — which we all should do, for all sorts of reasons — you are likely to encounter biting bugs. Most of the time the bites are just a nuisance. But besides the fact that sometimes they can be painful or itchy, bug bites can lead to illness — like Lyme disease from ticks, or Zika, malaria, or West Nile disease from mosquitoes. So preventing bites is a good idea for all of us, and certainly for children.

Simple precautions will help

Before talking about insect repellents, it’s important to remember that there are simple and effective precautions, nearly all of which don’t involve any chemicals. For example:

• Empty out any standing water outside your home. That’s where mosquitoes breed.
• Wear long-sleeved shirts and long pants if you are going to be in areas with lots of biting insects. If you treat clothes (and shoes and gear) with 0.5% permethrin, it can be helpful.
• Be aware that mosquitoes are most likely to be out at dusk and dawn, and plan activities accordingly.
• To avoid tick bites, avoid wooded and brushy areas and keep to the center of paths when you hike. Be sure to do a tick check when you come home — not just of all the people in your group, but also any pets or gear that came along. Taking a shower soon after arriving home can help with both tick checks and washing off any unattached ticks.

Make choices about insect repellent

Insect repellents can be very useful. Some are more effective than others, and some can have side effects, so it’s important to do your homework. The Environmental Protection Agency has a great interactive tool that can help you choose the best repellent for your particular situation.

The most effective repellent is DEET (N, N-diethyl-meta-toluamide). It works against both mosquitoes and ticks, and is definitely the go-to repellent if you really want or need to prevent bites. The higher the concentration, the longer it lasts: 10% will give you about two hours of coverage, while 30% can protect you for about five hours. The American Academy of Pediatrics (AAP) recommends not using more than 30% on kids, and not using any repellents on infants less than 2 months old.

The most common side effect is skin irritation, and if you ingest it (you never know with little kids) it can lead to nausea and vomiting. Eye irritation is possible, which is why you should never spray any repellent directly to the face, but rather put it on your hands and then carefully apply to the face. In very rare cases, like one in every 100 million users, DEET can lead to brain problems such as seizures if used in high doses. This is an incredibly rare side effect, and not something that should stop you from using it, especially if you are in an area with a lot of ticks, or an area with lots of disease-carrying mosquitoes.

Here are some alternatives with minimal to no side effects (eye irritation most common; avoid as noted above):

• oil of lemon eucalyptus, or PMD (the manmade alternative). This works nearly as well as DEET.
• picaridin, which works better against mosquitoes than ticks
• 2-undecanone
• IR-3535, the active ingredient in Avon products, although it is not very effective
• citronella, although it is even less effective.

Applying insect repellent — and sunscreen

Whatever you use, follow label directions and be sure that you are careful as you apply it to all exposed skin. It’s best to spray in an open area — and spray clothing too. Pump bottles and wipes with insect repellent may help you apply products carefully. Try to choose the best product for your situation so that you can apply it just once; the EPA tool is great for that. Don’t forget sunscreen; apply that first so your skin can absorb it.

The Centers for Disease Control and Prevention (CDC) has more information about applying insect repellent on children and preventing bites from mosquitoes and ticks.

Also visit the Harvard Health Publishing Lyme Wellness Initiative to learn about preventing –– or living with –– Lyme disease and other tick-borne illnesses.

About the Author

Claire McCarthy, MD, Senior Faculty Editor, Harvard Health Publishing

Claire McCarthy, MD, is a primary care pediatrician at Boston Children’s Hospital, and an assistant professor of pediatrics at Harvard Medical School. In addition to being a senior faculty editor for Harvard Health Publishing, Dr. McCarthy … See Full Bio View all posts by Claire McCarthy, MD