In the wake of research from the National Breast Cancer Foundation, NSW Illawarra region mum-of-three and breast cancer survivor Erryn Simms has called on everyone to take the time to check their bits.

Erryn first noticed a pea-sized lump in her breast shortly before Christmas 2018. She made a doctor's appointment in January, received her cancer diagnosis on her eldest daughter's eighth birthday, and had the cancer removed in February.

In the three weeks between her biopsy and operation, it had grown by a centimetre.

"It was a very aggressive type of cancer, and if I had left it, if it had gotten into my lymph nodes, who knows where I would be today," she said.

Following chemotherapy and radiation treatments, Erryn, of Wollongong, has appointments with specialists every four months that will continue for the next decade.

She had no family history, and was aged 34 when she first noticed the lump.

While she didn't perform specific self-checks, she says knowing her body and acting quickly saved her life.

"You don't have to check yourself perfectly, but be aware of what your normal is, so if something does change you'll pick it up quickly," she said.

"It might be a lump in your breast, or a changed freckle, or a change in your stools.

"Just check yourself, be body aware, know it can happen to you, your neighbour, your best friend or anyone."

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Erryn said one of the hardest parts of her diagnosis was breaking the news to her three daughters.

"At the time they were aged eight, five and 18 months," she said. "On the day my five-year-old started kindy we met with the surgeon.

"We picked her up from her first day at school and that night we told them I was sick. It was the toughest conversation.

"One day she asked me 'mum, are you going to die?'

"We'd been very honest with them, and I just said darling, I don't know.

"The fact I couldn't reassure her because I didn't want to give her false hope was tough."

The previously active mum had to step down from her beloved 'dance mum' duties, missed swimming carnivals and other special moments.

In addition to being sick from chemotherapy, if she caught any infection it would put her next round of treatment back, potentially giving cancer the opportunity to return.

Daughters Payten, 10, Mackenzie, 8, and Kennedy, 4, don't have the gene for breast cancer, and neither does Erryn.

If they or their friends are unfortunate enough to receive the same diagnosis in future, she hopes treatment options will have progressed.

To that end, she hopes anyone who is able will make a donation to the National Breast Cancer Foundation.

"Anything they can do to improve treatments and outcomes for people with breast cancer will help other cancers as well," she said.