The diagnosis has prompted Etheridge to cancel her planned fall tour, according to a statement on her Web site.
Doctors discovered the cancer in its early stages and have already begun treatment, with surgery planned as well.
"I am fortunate to be under a wonderful doctor's care and thankful that this was caught early," Etheridge said in a statement. "I am looking forward to a quick and full recovery."
The singer plans to recuperate at her Los Angeles home with her partner, actress Tammy Lynn Michaels, and her two children from a former relationship with Julie Cypher.
The two-time Grammy winner had been planning a seven-city tour beginning Friday night in Lowell, Mass. The tour was intended to promote her latest album, "Lucky," which was released in February, and "Lucky Live," a DVD and CD which was released this week.
There was no immediate word on whether Etheridge's health problem would affect plans for her upcoming ABC TV comedy or her role in the feature film "Southern Comfort."