It's usually not easy, but there are ways to get the information you want once you understand what you're up against.
The best way to win your mother's
doctor over -- and get her to open up -- is to first put yourself in her shoes and imagine the kinds of constraints that she's operating under. Most doctors are reluctant to share hunches; they want to wait until they have hard evidence before they tell you what they think is going on -- in part, to avoid lawsuits if they're wrong.
If your mother's prognosis isn't optimistic, her oncologist may also be reluctant to offer a specific prediction about how she thinks things will go -- both because there are always some people who do better than expected and because a positive attitude can contribute to a good, or better, outcome. If you suspect this is the case, tell her directly that you aren't afraid to hear negative or worrisome information, and that you and your mother intend to maintain a positive, hopeful attitude even if some of the pathological information is discouraging. Explain that you'd rather know everything and make your own decisions about what to worry about, and that this will not influence your mother's attitude toward healing. Hopefully, this will relieve her of the feeling that she needs to protect your mother.
Finally, oncologists never have as much time as they'd like to spend with each patient. An oncologist might be seeing 28 patients in one day, and each of them is desperately in need of help. If your mother's doctor were to outline all the potential disease paths, all the treatment options, and all the possible things that might happen, the appointment could take hours.
The best approach, usually, is to come into the office with your mother and say, "Here's what we know, and here are the top five questions we'd like answers to." Make those questions the ones that you really need the oncologist to answer; leave others for the support staff. For example, the office manager can often answer questions about insurance, and the nurse or pharmacist can answer questions about side effects of chemotherapy and other drugs.
It also helps to do a little research on your own and use the correct medical terms when you talk to your mother's oncologist. You might start out, for example, by saying, "We know it's osteosarcoma and that the average life span for someone at stage III is three to five years. But, naturally, we want to do everything we can to help her do much better than that…" Then the oncologist thinks to herself, "Okay, they're well informed, so I don't have to generalize." Telling the doctor what you do
know helps her realize that she can use specific terminology that will help you better understand your mother's cancer diagnosis.