The National Comprehensive Cancer Network (NCCN) is a consortium of 21 leading cancer centers across the country. They write clinical guidelines for oncologic care with panels of doctors who are some of the best minds in cancer care. As an active clinical urologist, I use their guidelines frequently to give my patients the most up to date, evidence based care.
If you are a clinician or interested patient here is a link to their clinical guidelines:
NCCN Clinical Guidelines
They encompass all major human cancers and are listed by site. Since I'm a urologist, I almost exclusively use the prostate, bladder, kidney, and testicular cancer guidelines.
The NCCN has also produced an excellent guideline for prostate cancer patients. Here's the link:
NCCN Patient Guidelines
It uses very clear language and starts from the basics. With so many treatment options out there, it is nice to have an unbiased resource for patients during such a difficult time in their lives.