Bone loss a side effect of breast cancer drugs

DEAR DR. ROACH: I am a 69year-old female breast cancer survivor. I’ve been taking Arimidex for five years, and plan to continue for another five. Through the years, my bone density scans have been normal, up until this year. I’m now on the edge of osteopenia.

My oncologist now recommends Prolia. After reading about the possible side effects, I am very hesitant to receive the injection. I feel like, at this point in life, I should just take my chances on the possibility of breaking a bone rather than expose myself to potential harm from Prolia. I’ve started daily vitamin D as well as increased calcium intake from food, rather than supplements.

What are your thoughts on this drug?

ANSWER: Anastrozole (Arimidex) is an aromatase inhibitor (AI): It works by preventing the body from converting androgens from the adrenal glands to estrogens, which are female hormones that encourage some breast cancers to grow.

However, estrogens also help keep bones strong, so it is common for post-menopausal women on anastrozole to develop bone loss leading eventually to osteopenia and finally to osteoporosis.

AIs like anastrozole increase the risk for hip fracture. A hip fracture is a major health risk: Oneyear mortality rates after hip fracture range from 14 per cent to 58 per cent. Preventing a hip fracture is critically important.

In osteoporosis, treatment with denusomab (Prolia) or bisphosphonates generally has more benefits than risks. I normally recommend against the use of these drugs in women with osteopenia; however, in women taking anastrozole, it is reasonable to consider the use of denosumab or a bisphosphonate in women with severe osteopenia or in those in whom the bone density is dropping rapidly.

It doesn’t sound like that is the case in you. However, you may have more risk factors for fracture than I know of, which may be why your oncologist is recommending treatment.

Certainly, I agree with the calcium intake, given your low bone density, and vitamin D supplementation may be appropriate if your vitamin D level is low or if you have additional risk. Any exercise is of benefit: Yoga and tai chi have been shown to be beneficial. However, weight-bearing exercises, especially higherimpact exercises, are even better for preventing bone loss.

Questions about breast cancer and its treatment are found in the booklet on that subject. To obtain a copy, write: Dr. Roach, Book No. 1101, 628 Virginia Dr., Orlando, Fla., U.S.A., 32803. Enclose a check or money order for C$6 with the recipient’s printed name and address. Allow four weeks for delivery.

DEAR DR. ROACH: I am 84 years old. A recent MRI shows that I have spondylolisthesis of the cervical spine. My main problem is loss of balance, and I get very tired after walking at a normal pace for 10 to 15 minutes. I have no back pain, and I think this is due to my daily back exercises. My neurologist has suggested that back surgery could correct my balance. Would surgery be worthwhile? Does surgery have benefits that last a reasonable period of time?

ANSWER: If you think of a simplified model of vertebrae as bricks on top of one another, spondylolisthesis is when the bricks don’t line up: One sticks out further in front, while another sticks out behind. Surgery for spondylolisthesis is usually performed only when there is intractable pain, or when there are progressive symptoms, especially weakness.

I am puzzled why your neurologist recommends that you consider surgery for balance. I certainly would recommend a trial of balance exercises (different from, and in addition to, your regular back exercises), supervised by a trained physical or occupational therapist. I am exceedingly cautious about recommending spine surgery, especially to someone in their 80s, where surgical complication rates tend to be higher.

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