In this paper the authors have extended the methodology for temporal analysis of online forums and applied the methodology to six online cancer forums (melanoma, prostate cancer, testicular cancer, ovarian cancer and breast cancer). The goal was to develop, apply and improve methods that quantify the responsiveness of the interactions in online forums in order to identify the users and topics that promote use and usefulness of these online medical communities. The evolutional stages that gauge when a forum is expanding, contracting, or in a state of equilibrium were considered. The response function was thought to be an approximation of a discussion group's utility to its members. By applying the evolutionary phase algorithm, it was determined that two out of six of the forums are in contracting phases, while four are in their largest growth phase. By analyzing the topics of the influential threads, the authors conclude that cancer treatment discussions as well as stage IV cancer discussions promote growth in the forums. It is observed that the discussion of treatment rather than diagnosis is important to help a cancer forum thrive.