Can I publish multiple papers with same methodology but different topics?
In general, the test for whether a result is publishable is whether it advances the state of human knowledge.  

Thus, if X is a new approach that contributes to knowledge about Problem 1, then it could readily be published in either a methodology-centric venue or a problem-centric venue.  If X is applied to produce new knowledge about Problem 2, then that's less interesting from a methodology perspective (though it may still be interesting, depending on circumstances), but absolutely relevant for Problem 2.

So if the approach really is useful for learning about lots of different types of cancer, it's potentially publishable for each type.  At some point, though, generalization becomes more interesting, and it would be appropriate to write a (much higher impact) paper on the applicability of the approach for learning about all cancers.