MONTREAL -- A health advocacy group is accusing the Quebec government of withholding potentially lifesaving information from women as they say some doctors aren't sharing critical details about breast density when getting mammograms.

Annie Slight is a health advocate whose journey to fight for women's health rights began eight years ago when she found a lump in her breast.

She went for a mammogram and the doctor told her the results were normal, but the mass kept growing.

A year-and-a-half later, she went back to her doctor, who did more tests and discovered she had breast cancer.

"I was obviously in shock," she said. "I was only 42 years old. I had no family history, no gene mutations, nothing, so it was very unexpected."

The first mammogram never picked up the cancer because Slight has dense breast tissue.

"Dense tissue appears white on a mammogram and so does cancer," she said. "So in my case, it was white on white. My surgeon said when we look at your mammogram, it's like looking for a polar bear in a snowstorm. We just don't see anything."

Almost half of women over 40 have dense breast tissue, and in Quebec, family doctors are advised about breast density but do not always pass the information on to the patient.

Radiologist Donald Edde said this fact makes no sense.

"These women have the fundamental right to be told you have dense breasts, and then they can go to ultrasound to see whether there's anything behind it," said Edde.

Knowing mammograms weakness in diagnosing those with dense breasts may have given Slight over a year more to fight the cancer.

"The difference would have been very likely no chemotherapy," she said. "It would have been just radiation and a lumpectomy."

The group Dense Breasts Canada is asking Quebec Health Minister Danielle McCann to make sure doctors inform patients about breast density so they can make more informed choices. A spokesperson for the minister said in an e-mail that they're looking into making changings, but not before spring 2021.

Slight is baffled.

"In BC and PEI, once the government committed to breast density notification, it took them two weeks," she said. "Early detection of breast cancer should not depend on where we live. It shouldn't be that women of certain provinces are informed and women of Quebec have to wait until 2021."