Any of us who have had chemotherapy have likely wondered how the appropriate dose is calculated. There is a standard formula, plugging in height and weight, that gives the answer. Some of us have had the experience of needing to reduce the planned dose on a particular treatment day because of lower than optimal blood counts. This is a not infrequent occurrence. Sometimes our doctors opt to delay treatment for a week or so to give the counts time to rise, but sometimes they lower the dose for that cycle.
Years ago, I remember hearing stories about less than optimal outcomes because oncologists sometimes (NOT AAT BIDMC OR OTHER GOOD HOSPITALS) lowered the dose consistently in order to minimize side effects. It was about : "Oh, poor thing, we will make this easier on you." I suspect that zero patients would opt for a slightly easier course over taking the treatment that is hopefully going to smash the cancer. I haven't heard anything remotely like this for a long time and hope it no longer happens.
This is an interesting article from Web MD about all of this:
What is the Right Amount of Chemotherapy?
By Richard C. Frank, MD
“How does my doctor know what dose of chemotherapy is right for me?” This is a very common question among
cancer patients. It is also a very good one.
Every person is unique, of course – mentally, emotionally and physically. We each have a unique genetic makeup and each of our bodies has been subjected to the rigors of life in unique ways. We differ in our general health, organ functioning and, especially, in the ways our bodies process medications. Add to this the fact every cancer is unique in its genetic makeup and sensitivity to anti-cancer drugs. So how can oncologists accurately know the right dose of chemotherapy to give each patient?
The answer is, we really don’t.
The recommended starting dose of every cancer drug is determined in clinical trials that establish the “maximum
tolerated dose” for each drug. This is usually one dose level lower than the dose that caused excessive side effects. This is certainly not an optimal way to determine the best dose for each patient. The biggest problem, however, is that these clinical trials include highly selected patients who are usually in the best of health, not the elderly or infirmed. Once the medicines become FDA approved and hit “the real world” of average people with cancer, dosages of cancer fighting drugs are ultimately reduced in approximately 20-30% of cases. This is because many patients have other health problems besides cancer or are over 75 years of age, populations very susceptible to severe side effects from chemotherapy. Of course even the healthiest individuals may experience unanticipated side effects and require dose reduction.