Perhaps you should try some spelling variations:
"5 ppm decrease" » "5 ppm decreased" (Expand Search), "5 ppm increase" (Expand Search)
"a point decrease" » "a point decreased" (Expand Search), "a point increase" (Expand Search)
"_ cd4 decrease" » "_ cd4 decreased" (Expand Search), "_ cd4 increase" (Expand Search)
"_ breast decrease" » "_ breast decreased" (Expand Search), "_ breast increase" (Expand Search)

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("5 ppm decrease") OR ((((("a point decrease") OR ("_ cd4 decrease"))) OR ("_ breast decrease"))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"5 ppm decrease\") OR (((((\"a point decrease\") OR (\"_ cd4 decrease\"))) OR (\"_ breast decrease\"))))".
• Removing quotes may allow a broader search: (( 5 ppm decrease ) OR ((((( a point decrease ) OR ( _ cd4 decrease ))) OR ( _ breast decrease )))).
• Adding a wildcard symbol may retrieve word variants: (("5 ppm decrease") OR ((((("a point decrease") OR ("_ cd4 decrease"))) OR ("_ breast decrease"))))*.