The board has ordered a committee of the College of Physicians and Surgeons of Ontario to reconsider its decision on Dr. Barbara Heartwell.
Laurie Johnston complained to the college that Heartwell performed an unnecessary mastectomy on her in 2009 after the doctor admitted she misread the results of a biopsy that found Johnston didn't have cancer.
The college committee found Heartwell made a "significant error" and ordered her to be formally cautioned by the college, not reprimanded or disciplined.
Johnston appealed to the Health Professions Appeal and Review Board, which noted in a ruling this month that prior decisions involving Heartwell are neither referenced nor discussed in the committee’s finding.
The board said the committee should have addressed those complaints, given that Johnston had raised the case of another woman whose healthy breast was removed by Heartwell years earlier.
Janice Laporte, whose breast was removed by Heartwell in 2001, was told a week after her surgery that she didn't have cancer.
She sued Heartwell, but Laporte cannot discuss the outcome because of a confidentiality clause.
Heartwell's lawyer told the college committee that Heartwell "denied the assertion that she had previously performed an unnecessary mastectomy," the board wrote in its decision.
Johnston settled a lawsuit against Heartwell, the pathologist Dr. Olive Williams and two hospitals. Details cannot be disclosed, but Johnston had been seeking $2.2 million in damages.
Johnston had a biopsy on a mass in her left breast in October 2009, and while the pathological diagnosis in the report was "portions of fibroadenoma," a non-cancerous tumour, the report stated "ducctal carcinoma" under the clinical information section.
Heartwell performed both Johnston and Laporte's surgeries at Hotel-Dieu Grace Hospital in Windsor.
The medical college, the hospital and the province launched investigations into Heartwell and Williams when both Johnston and Laporte came forward.
The provincial investigation uncovered "significant concerns" with Williams' work. She was suspended and later resigned from Hotel-Dieu and has decided not to renew her medical licence.
The investigation largely cleared Heartwell, who has resumed work at Hotel-Dieu.
Earlier this year another pathology mix-up led to Heartwell performing an unnecessary lumpectomy. The hospital stressed that it was a pathology department error and Heartwell was not at fault.
In its decision the board said it is concerning that the college committee didn't reference prior decisions about Heartwell, especially since Johnston told them about Laporte's case.
"Given the serious nature of the allegation and the similarity to the complaint before the committee, the committee needed to address the matter," the board found.
"The board is concerned with the transparency of the committee's decision, and this is especially problematic in light of the parallel investigations that were going on in this case."
The committee addressed Laporte's case only to note that doctors are not obligated to disclose their complication rates or discuss previous surgical errors to their patients.
The board ordered the committee to reconsider its conclusion that Heartwell did not expose other patients to harm or injury.
The board can confirm a committee decision, make recommendations to the committee or require it to make certain findings.