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 » deccan microbiota, fecal microbiota, human microbiota
bat microbiota » gut microbiota, breast microbiota, plant 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 (bat microbiota))) OR (((cancer microbiota) OR (cancer microbiology)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "immunosuppression ((((can microbiota) OR (bat microbiota))) or (((cancer microbiota) or (cancer microbiology))))".
• Adding a wildcard symbol may retrieve word variants: immunosuppression ((((can microbiota) OR (bat microbiota))) or (((cancer microbiota) or (cancer microbiology))))*.