Breast data limited by consents

By REBECCA WALSH AND NZPA

A requirement to gain informed consent from patients before they are included on an Auckland breast cancer register limits the "absolute confidence" researchers can have in the data, a leading oncologist says.

The Auckland Breast Cancer Study Group, which set up the register, is seeking approval from the region's ethics committee to collect information without patients' consent.

Dr Vernon Harvey, head of medical oncology at Auckland Hospital and a member of the group, said that at the moment each patient had to be approached individually by her doctor for consent, which took time.

About 2600 women are on the Auckland register.

Of the 1497 patients identified as eligible for the register between June 2000 and June 2002, 1204 gave consent, 18 refused, 18 died before consent could be sought and the remaining 257 were not asked by their clinicians, Dr Harvey said.

"It limits the absolute confidence we can have in the data. If we are missing cases, we don't know if we have an average picture across the whole group.

"Maybe we are missing all the difficult ones, all the big ones, all the nasty ones, and therefore our picture looks better than the true picture."

A database started in 1976 had to close in 1985 after concerns were expressed over privacy issues.

The register was set up three years ago but consent was required for a woman's records to be transferred to it.

Dr Harvey said members of the group were due to meet the ethics committee to discuss the issue but he did not expect a decision immediately.

Register project co-ordinator Ora Pellett said privacy at all costs was a problem because people did not understand what all the costs were.

The result would be an inefficient health system, Dr Pellett said.

"The register only looks at medical information relating to the breast cancers and myself (and one other person) are both bound by the same rules of confidentiality as the patients' clinicians."

The register could identify important trends, she said.

The group's research, published in the New Zealand Medical Journal today, found that women under 40 tended to have more aggressive breast cancer: 53 per cent of patients under 40 had a grade-three tumour compared with 26.8 per cent in women over 40.

Dr Harvey said that was possibly because cancer tended to be a disease of older age and when it occurred in younger people "more had gone wrong to cause the cancer in the first place".

The data also showed tumours were being detected when they were a lot smaller - about half the tumours were less than 2cm when first diagnosed - something the researchers put down to greater awareness of breast cancer and breast screening.

About 56 per cent of women with invasive cancer had a mastectomy.

Breast cancer

* About 2000 NZ women are diagnosed with breast cancer each year, and about 600 die from it.

* Incidence expected to rise because of the ageing population, delayed child-bearing and women having fewer babies - factors that increase breast cancer risk.

* Otago University says death rate falling but still 28 per cent higher than Australia's.

* Ministry of Health says 80 per cent of patients alive five years after treatment.