Complement components form a plasma innate immune cascade but could also serve as multitasking proteins, as they have functions beyond this system. Here, we show that complement FH is locally expressed by multiple types of human tumors. We provide a paradigm shift for the impact of FH on cancer progression, showing a previously unrecognized, intracellular function of FH outside the complement cascade, while the canonical, complement-regulatory function had no effect. Int-FH served as a driver of the proliferation and migration of ccRCC and lung ADK cells but not of normal cells or lung SCC cells. The presence of int-FH staining in tumor cells indicated poor prognosis for ccRCC and lung ADK. Thus, the invention relates to a method for predicting the survival time of a patient suffering from a cancer, comprising i) determining in a sample obtained from the patient the expression level of int-FH ii) comparing the expression level determined at step i) with its predetermined reference value and iii) providing a prognosis when the expression level determined at step i) is modulated compared to its predetermined reference value.