The salient point is that the overcrowding of drug candidates in cancer is more extreme than in other indications. This conclusion is undeniable regardless of how you parse the data from PhRMA and other similar databases.
You can still make money investing in biotech companies who are exclusively pursuing cancer if you really know what you are doing and you enjoy more than a modicum of lucky breaks; however, the odds of making money consistently by investing in this manner are worse than in almost any other arena of the biotech universe, IMO.
“The efficient-market hypothesis may be the foremost piece of B.S. ever promulgated in any area of human knowledge!”