WITH three critical illness policies under her belt, she assumed her insurance coverage was comprehensive enough.

Ms Theresa Tan's policies with Prudential saw her dutifully forking out a total of $600 in insurance premiums every month.

She believed she had forked out about $77,000 for them over the years. But when it came to coverage, the mother of three, 42, thought wrong.

She was diagnosed with early stage breast cancer, or stage 0, in June.

That same month, she went through a 12-hour operation at Gleneagles Hospital to remove her right breast and to have reconstructive surgery done, using skin and fat from her stomach.

The operation and hospitalisation cost $30,000 and was covered by another insurance policy she had with Aviva.

Ms Tan then tried submitting her claim to Prudential this month for loss or potential loss of income.

She thought she could claim up to $100,000 for one policy and up to $107,000 for another policy.

But her claims were rejected by Prudential, which explained to her in a letter that her condition was non-invasive and "does not fulfil the definition of cancer".

Ms Tan's condition is known as ductal carcinoma in situ (DCIS) in her right breast.

This is a condition where the cancer starts in the milk ducts of the breast. It was considered non-invasive at that stage as the cancer had not spread beyond the milk ducts into the surrounding breast tissue.

In Ms Tan's case, she had a mastectomy because the cancer cells were located in various parts of her breast.

Prudential's decision has surprised Ms Tan, especially since her family's medical history was known to her insurance agents.

Her mother was diagnosed with breast cancer when she was 19 years old. She subsequently died in 2003 after a long battle against cancer.

Her mother's illness was what made Ms Tan buy her first insurance policy when she was 22.

Said Ms Tan, who is the co-partner of nanzinc.com, an online portal set up with her friend, entrepreneur Nanz Chong-Komo: "Fortunately, my mum had a pension plan so her treatment was covered.

"But seeing what she went through and given I was not under pension, I wanted to make sure that I was provided for.

"I thought by buying three policies I was covering myself in every circumstance, but it didn't work out that way."

She claimed the gaps in her policy - it did not cover early stage cancer - was not explained to her by her insurance agents.

Neither was the option of a rider to supplement her existing policies offered.