As a mother of young children, Karen Hall is used to asking for things more than once — but she did not expect to have to request a mammogram over and again.

Key points: A 33-year-old woman was referred by her GP to an imaging clinic after finding a lump in her breast

A 33-year-old woman was referred by her GP to an imaging clinic after finding a lump in her breast She was refused two mammograms and was told she was "too young for cancer"

She was refused two mammograms and was told she was "too young for cancer" She was eventually diagnosed with stage three breast cancer

After finding a breast lump during a self-check, Ms Hall saw her GP who referred her to the I-MED imaging clinic at Latrobe Regional Hospital in eastern Victoria for an ultrasound and mammogram.

The ultrasound turned up no abnormality and to her shock, she was refused the mammogram on the basis that she was "too young for cancer".

"They said 'we'll leave it six months and if the lump gets any bigger, come back,'" Ms Hall said.

Trusting her instincts, Ms Hall went back to her GP, who referred her on to a breast specialist who formally requested a mammogram and a biopsy.

Returning to the imaging clinic a week later, Ms Hall was again refused the mammogram because of her age.

This time, she stood her ground.

"That's not good enough," Ms Hall said she told the clinic.

"I'm not leaving until I get the information the surgeon has requested from you."

The clinic eventually did perform the mammogram and biopsy, as requested by her specialist.

Several days later, Ms Hall, then 33, learned she had stage three breast cancer.

She has undergone several surgeries since then.

"I knew I was going to be out of pocket a few hundred dollars — that wasn't the issue," Ms Hall said.

"The issue was that they were flat out refusing to do it because I was 'too young for breast cancer'.

"If I had listened the first time and waited six months, I don't know where I'd be."

I-MED says it doesn't refuse valid referral requests

I-MED Regional general manager, Mark Simpson, said that the service was unable to discuss specific patient cases, due to privacy obligations.

Mr Simpson said the service was based on referrals, and services could only be provided following the request by a patient's GP or specialist doctor.

"Our clinic would not refuse a valid referral request," he said.

Breast screening accuracy increases in women over 40

Gippsland BreastScreen Victoria Gippsland manager Julie Foat said this case was unusual.

Karen Hall was initially refused a mammogram before being diagnosed with stage three breast cancer at 33 years old. ( ABC Gippsland: Rio Davis )

Ms Foat said there was no evidence to suggest mammograms were effective in reducing mortality rates in the under-40 age group.

"Our population screening is for women over the age of 40 and that's because, under the age of 40 the breast appears on an image as white, and breast cancers appear as white on an image," Ms Foat said.

According to statistics from the Australian Institute of Health and Welfare, the number of women under 40 diagnosed with breast cancer has stayed between 11 and 13 per 100,000 women for almost 30 years.

However, Cancer Council cancer control policy director Megan Varlow said women under the age of 40 were a statistically significant group in breast cancer diagnoses.

"There are a fair number of women who experience breast cancer below the age of 40," she said.

"It's just that after 40, it's much more common and much easier to detect using mammograms.

"It is concerning to hear that a woman with symptoms and a referral from her GP was refused service."

Twelve months since her diagnosis, Ms Hall is settling back into normalcy.

She has filed a complaint and has a simple message for other young women.

"Trust your instincts, stand your ground," she said.