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To your good health

'Tumor seeding' very rarely occurs during biopsies

DEAR DR. ROACH: I read your recent column on prostate biopsies. I’m no doctor, but I’d advise against them. My boyfriend got a biopsy in 2012, which I believe caused his cancer to spread beyond his prostate into his bones. He died three years later in 2015.

Think about this: A needle is inserted to extract cells so that they can be tested. When the needle is pulled out with its open end, and cancer is present, cells in the needle can then come out of the open end, causing cancer to spread throughout the prostate. It may be rare, but this is documented (tumor seeding). — B.S.

ANSWER: I must disagree with you in the strongest possible terms. A biopsy is an essential piece of information in order to know how to treat a patient. Over decades and tens of millions of biopsies, there have been 42 total cases of seeding that were reported worldwide from the needle tract. This extremely rare event shouldn’t prevent a man from understanding what the best treatment of his prostate cancer will be. Other studies haven’t shown an association between a biopsy and a subsequent spread of the disease.

I’m very sorry about your boyfriend, but given the slow growth rate of prostate cancer, it’s likely your boyfriend had prostate cancer that spread to his bones years before the biopsy was done.

DEAR DR. ROACH: I read about a new weight-loss drug that is still in its clinical trials. It’s called retatrutide, and it may have the ability to reduce body weight by as much as 28% over a relatively short period of time. What are some of the dangers of losing weight too quickly? — B.G.

ANSWER: I also read the initial studies on retatrutide, and I’m very impressed with the results. The level of weight loss that was seen is in the range of what is expected with bariatric surgery. It acts similar to semaglutide (Wegovy) by stimulating the GLP-1 receptor, but like tirzepatide (Zepbound), it also stimulates the GIP receptor. Unlike either of these drugs, it also acts on a third receptor, glucagon, and this combined action has shown remarkable results, with nearly two-thirds of study subjects no longer being classified as obese while on the drug.

You’re wise to ask about the side effects of so much weight loss. Regardless of the underlying reason for the weight loss, there’s the potential for harm whether you lose weight through medications, surgery, or careful adherence to diet and exercise. Gallstones are common during rapid weight loss, and some experts use medication to prevent them.

Bone mass can be lost by both men and women during weight loss. Making sure that a person gets enough protein and vitamin D can reduce this, and people who are at risk (such as those who had low bone mass to begin with) may be recommended medications to prevent the progression to osteoporosis.

We’ve seen loss of muscle mass with the existing GLP-1 drugs. To some extent, this is because a person no longer carts around so much weight. Regular exercise, especially weight lifting, and adequate protein intake can help reduce muscle loss as well.

When eating only a few amount of calories to lose weight, a person needs to be careful that they get all the micronutrients they need. I recommend working with a registered dietician or nutritionist to avoid deficiencies.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu. (c) 2026 North America Syndicate Inc.

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