WASHINGTON — Likening sexual assault in the Air Force’s ranks to a cancer, the service’s top officer resolved Wednesday to tackle the problem by screening personnel more carefully and ending bad behaviors like binge drinking that can lead to misconduct.

But General Mark Welsh, the Air Force chief of staff, underscored the challenge by telling a House oversight committee that the service recorded a disturbing number of reports of sexual assault last year even as it worked to curb misconduct following a sex scandal at its training headquarters in Texas.