A political aide has testified at Newfoundland and Labrador's breast cancer inquiry that he was left speechless when told in 2005 that many cancer patients could have benefited from more appropriate treatment before they died.

Darrell Hynes, testifying Wednesday at the Cameron inquiry, said he was startled to learn in a November 2005 meeting that mistakes with hormone receptor tests might have directly affected patients before they lost their battle with breast cancer.

Hynes said oncologist Kara Laing met with officials, including John Ottenheimer, the minister of health at the time, to update them on the rerunning of hundreds of estrogen receptor and progesterone receptor, or ER/PR, tests.

The tests are given to determine whether a patient can benefit from the antihormonal therapy Tamoxifen.

Hynes, who was Ottenheimer's executive assistant, said he asked Laing whether some of the patients who had died could have benefited had their tests not been faulty.

"Yes, that's what she indicated," Hynes told inquiry co-counsel Sandra Chaytor.

"Was there any other discussion around the ER/PR issue?" Chaytor asked Hynes.

"No, because I don't know if I could've asked any more questions after hearing that," Hynes told the inquiry.

"So I take it that stood out?" Chaytor asked.

"Yes, very much so," Hynes replied.

"I remember I looked at the minister, and Minister Ottenheimer's expression just drained away, and I'm sure he looked as bad as I looked, because I think it was a startling revelation in my mind."

Laing has not yet testified at the inquiry.

Minister was 'very troubled'

The provincial government said in March that 383 patients received flawed hormone receptor test results, and that 108 of them were dead. It's not clear how many of them would have benefited from a change in therapy.

Justice Margaret Cameron has been hearing evidence since March on what went wrong with Eastern Health's hormone receptor testing program between 1997 and 2005, and with how the regional health authority and government officials responded to the crisis.

Hynes, who would later serve as executive assistant to Ottenheimer's successor, Tom Osborne, said his political antennae went up the moment he was first told about breast cancer tests in the summer of 2005.

Hynes testified that Ottenheimer was "very troubled" by the revelations that as many as 1,500 patients could be affected.

"I think he recognized that this could be a huge, you know, very significant issue in health care in the province," Hynes said.

Echoing earlier testimony from various witnesses, Hynes said that senior managers and physicians from Eastern Health persuaded Ottenheimer that the mistakes should not be made public until results of retests were in and all affected patients were notified by letter.

But Hynes testified that months later, when a patient letter had yet to be distributed, he grew increasingly suspicious.

"I began to wonder if Eastern Health ever wanted to send a letter in the first place," he said.

"There was an impression left that a letter would be prepared at some point, and as the time went on, you had to think that it got further and further from Eastern Health's perspective, and you had to wonder if this is something they still are prepared to do."

Patients were not contacted formally until after media reports in October 2005.

As well, the retesting process took many more months than expected.