I don't see the flaxseed/cottage cheese combo ever causing cancer or making cancer worse.  A bad diet will do that though.  Sounds like you eat a pretty healthy diet for the most part.  Just avoid those sugar binges and make sure that you avoid processed meats.  Organic free range type meats would be much, much better than feedlot type meats.

Insofar as rogue cancer cells, many believe that we all have cancer type cells in our body all the time but they are taken care of by our natural first line of defense against cancer and other illness - our immune system.  Now, here is the rub:  some cancers can take up to eight years from the time they gain a foothold until they grow large enough to be detected, so it is a good idea in my opinion to take measures to eliminate any possible "hidden" cancers.  That is why a couple of times each year I will go on a one-two month strong anti-cancer regimen and do things such as take oleander extract, colloidal silver, Cell Forte (inositol/IP6 with extras), extra curcumin  and a good blood/body cleanser such as Jon Barron's Blood Support and/or Essiac tea.

Consuming plenty of watermelon should help your kidneys.  If it were me, I would do periodic liver flushes and also take items that are good for your liver as well as keep your bile ducts open and flowing to eliminate toxins.  Milk thistle is a must.  Other good items include selenium, beetroot juice, curcumin and coconut oil.

Some good natural chelators for heavy metals and other toxins are chlorella, cilantro, parsley and apple pectin.