Perhaps you should try some spelling variations:
cancer microbiology » water microbiology, cave microbiology, ulcer microbiology
cancer microbiota » cancer microbiome, cancer microrna, cecal microbiota
can microbiota » bat microbiota, deccan microbiota, fecal microbiota

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: immunosuppression ((can microbiota) OR (((cancer microbiota) OR (cancer microbiology)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "immunosuppression ((can microbiota) or (((cancer microbiota) OR (cancer microbiology))))".
• Adding a wildcard symbol may retrieve word variants: immunosuppression ((can microbiota) or (((cancer microbiota) OR (cancer microbiology))))*.