DEAR DR. ROACH: Have you heard that lymphoma patients are more likely than others to develop blood clots after surgery? I nearly died of a pulmonary embolus six days after hernia surgery. I have indolent non-Hodgkin’s lymphoma and never have had chemotherapy or radiation treatment. — P.R.

ANSWER: People with many different types of cancers are at higher risk for blood clotting. Those with cancer of the pancreas, colon, stomach, lung, kidney or brain are among the highest risk. Blood cancers, like leukemia and lymphoma, also increase the risk of a blood clot. Surgery already increases blood clot risk, but cancer further increases the risk of blood clots. The combination of cancer, even an indolent lymphoma, and routine surgery imparts about a 6 percent risk of blood clots, which is high enough that routine anticoagulation certainly should be considered. People with cancer should have a discussion with their surgeon about anticoagulation around surgery.

DEAR DR. ROACH: Maybe you will be able to figure out what is ailing my mom. She is 87 and suffers from lots of health issues, but excessive sweating is the most exhausting and debilitating. Several times a day (and night), her clothes get soaking wet and she has to change them. It’s been going on for almost two years. And because of sweating and a weak immune system, she easily catches cold.

She lives in Russia, my home country, and doctors there don’t know why it is happening or how to help her. I read online that the thyroid gland might be one of the reasons for the excessive sweating, but it was checked by an endocrine doctor and was OK.

Soon I am going back to my home country, and I would like to help. I would appreciate it very much if you have any ideas about my mother’s condition or advice as to what can be done to alleviate her excessive sweating, as she suffers from it so much. — L.A.

ANSWER: I’m afraid I can’t figure it out from the information you gave. Many conditions can cause night sweats, especially chronic infections (tuberculosis is the classic cause), inflammatory conditions (like rheumatoid arthritis), tumors (such as lymphoma), hormonal changes (not just thyroid, but estrogen loss and excess adrenaline), atrial fibrillation and anxiety states. Just being overweight predisposes a person to night sweats, and some medications can cause them. Finding the diagnosis requires skill, patience and judicious use of the laboratory.

I wish I could help, but I would need to do a careful history and exam. I can’t even suggest a treatment to stop it without having a good idea of what is causing it.

The booklet on thyroid gland problems explains this and other common thyroid illnesses. Readers can obtain a copy by writing: Dr. Roach — No. 401, 628 Virginia Dr., Orlando, FL 32803. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DR. ROACH WRITES: In June I advised J.H., who was complaining about nasal congestion at night, to avoid allergens. Several readers wrote in to tell me that water is the key — water in the air (from a humidifier), water in the nose (from a saline spray) and just a glass of water at the bedside. Strips of tape to hold open the nostrils, available commercially or ones you can make yourself, help many but not everybody. These are cheap, easy, have few if any side effects and might help. As always, I thank my readers who teach me helpful information.

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 or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.