Cancer diagnoses and deaths continued to decline in the U.S., according to the latest available data, helped by efforts to reduce risk, provide early detection and develop therapies.

The report, from a group of cancer and health organizations including the National Cancer Institute, trumpets the successes of improved screening and comes amid calls for less and later screening for breast and cervical cancers. A federally funded task force created an uproar last month when it said women could wait until they are older to begin...