[JessicaV]

I sympathise with the concern about having to have chemo too if you want trastuzumab, and the principle of a blanket treatment for all that is not fine-tuned to the best needs of the individual patient.

I think part of the reason for this is that the only treatment regimes the oncologists can offer with any sort of confidence are the ones that have been tested out on hundreds of people over quite a few years ie in large trials. If the oncologist changes any part of the regime from what was used in the trial, they are immediately using a totally untried treatment which could be either useless or dangerous. When they stick to what has been shown to be effective for someone like the patient in question, they can know a lot more about what side effects to expect, what tests to administer etc. They know the chances of it working to get rid of the cancer in question. My onc says that reducing dosage of anticancer drugs to less than 86% of the recommended protocol significantly reduces effectiveness.

The other part of the problem is that ethics committees who have to approve research trials (I understand the FDA uses this process though maybe they call them something different)generally will not permit any trial to start unless it offers all participants a good proven treatment. So it would have been initially hard for researchers to get approval for a herceptin-only treatment, until the drug becomes so well recognised as a good proven treatment on its own for patients with a particular kind/size/etc of tumor. In their wish to protect us the watchdogs slow down the approval of the sort of treatment you advocate.

The more different trials are done of different combinations, and the more the researchers manage to trial different protocols/regimes of drugs etc, the more options they can use with reasonable confidence they will work.
Carboplatin and Taxotere were used together with Herceptin in the big trial that finally proved there was a good chemo alternative to the heart-damaging andriamycin type drugs. Those particular chemo drugs were chosen because there were helpful interactions between them and herceptin and the HER2+ tumor that made the combination more effective. They were not just picked at random.