Comedian Wanda Sykes discovered she had ductal carcinoma when she had breast reduction surgery at age 47. And actress Shannon Doherty started her ongoing battle with breast cancer at age 44. Neither woman had their cancer identified by a routine mammogram.

"Early detection is going to make your prognosis better," says Doherty. "Maybe I wouldn't have had the surgeries ... or the chemo I've had."

Researchers in Canada agree. A study published in the journal Current Oncology looked at data on more than 55,000 Canadian women ages 40-49 and 50-59 who were diagnosed with breast cancer between 2011 and 2017.

They found that since 2011 when screening guidelines changed to say mammograms weren't recommended for women 40 to 49, there was a 12.6% increase in the diagnosis of stage 2 breast cancer for women in their 40s and a 10.3% increase in the diagnosis of stage 4 breast cancers for women in their 50s. Meanwhile, diagnosis for highly treatable stage 1 breast cancer declined.

Higher stage numbers mean more spread — you want zero or stage 1 when you get a positive mammogram.

The U.S. Preventive Services Task Force says "women ... may choose to begin screening once every two years between the ages of 40 and 49 years."

The American Cancer Society says women ages 40-44 have the option of an annual mammogram; those ages 45-54 should get annual mammograms; and women 55 and older can opt for every two years. 

Talk to your doctor about your preferences and risks, and what schedule you should follow. Then follow it.