Ask the Expert: Fosamax vs. Forteo

Health Professional

Patient Question:
Hello. I've been on Fosamax for 6 years and as of now, my deviations are as bad as they were when I first started; any gains were obliterated after menopause. I'm way into the high fracture risk in all 3 sites. eg -3.6 for back, etc. My doctors have been encouraging me to use Forteo. I'm totally freaked about the bone cancer risk and have such little faith in the FDA. The drug has been in use only three years. Isn't that way too short a time to see if anyone's going to develop this fatal side effect?

I'm in excellent shape - I  work out, eat well, and do all the right things. I'm strong and have no pain. I feel like everything will work to keep my body from breaking, even if my bones are brittle" my muscles/ligaments, etc are strong and secure. Why risk the bone cancer? Please help, and thank you!

Dr. Gonter's Response:

There are a few important issues that are raised here. I will discuss each of these and hopefully will give you enough information to allow you to have an educated discussion and to make a well-informed decision with your physician.

First of all, it is real nice to see increases in bone density when one takes a medication for their osteoporosis; however, unfortunately, that is not always the case. I often see panicked and distraught individuals on many years of medication, without any significant changes in their bone density (DXA). In reality, although important, the DXA is not the only factor that fractures are based upon. Just because one has osteoporosis by bone density, it doesn't mean it will ever lead to a fracture. There are many individuals with a low bone density on DXA who never break bones with extensive falls, and there are those with relatively normal bone densities who fracture with minimal trauma.

Fracture risk is made of numerous factors. Two of these are quantity and quality. Bone quantity consists of density and size, which together constitute bone mass. This is what is attempted to be measured with a standard bone densitometry machine (DXA). This is the most important component of fracture risk, but not the only factor.

Bone quality consists of numerous factors. These include bone turnover (how much and how fast bone is added and removed), bone size and geometry (greater size = greater strength) and the microachitecture (interconnecting structure, i.e. cross links between bone) and the type of mineralization that is in the bone structure (i.e. fluoride increased bone density, but causes increased fracture risk).

Other important factors are age, genetics and history of previous fractures.

As far as the risk from Forteo, I have covered that extensively in a previous blog (see November 2006). As in any situation, one must evaluate risk and benefit and make an informed decision.

Osteoporosis is a silent disease, until it strikes. Unfortunately, a fracture has disastrous effects and can significantly change a person's life. This is similar to high blood pressure where it may not be recognized until a heart attack or a stroke occurs. Even though one feels well, it is important to manage the disease, as is appropriate, due to the high incidence of fractures in the untreated "healthy" individuals.