Health expert says Tayside breast cancer report ‘probably flawed’.

Professor maintains figures were ‘best that could be done’

A leading cancer specialist behind a report which warned breast cancer patients in Tayside were put at increased risk of relapse said the findings were “flawed, probably, but the best that could be done”.

Professor David Cameron was part of a Scottish Government-commissioned review group asked to carry out an assessment into lower-than-standard chemotherapy doses offered between December 2016 and April this year.

The report said nearly 200 patients were put at a 1 to 2% increased risk of seeing their cancer return as a result of their treatment.

However, in correspondence seen by The Courier, Prof Cameron outlined how the review group “assumed a roughly linear benefit” of providing higher doses, despite not being certain if this was correct.

The specialist wrote the “key thing was to come up with an estimate to avoid alarming everyone” because “patients don’t like to hear that they perhaps got less effective therapy”.

He said: “We know that lowering the doses of chemo reduces the effect.

“But it is not known if this is linear or sigmoid (where the rate slows to a curve) or what, because of course clinical trials are not mathematical formulae, but ways of generating point estimates of effects.

“So we then assumed the maximum effect is seen with the highest deliverable dose (100mg/me) and assumed a roughly linear benefit. Flawed, probably, but the best that could be done really.”

Patients and families have repeatedly requested the methodology used to find the increased recurrence rate.

In May, a cancer expert from Manchester described it as “absolute rubbish”.

Prof Cameron was contacted by The Courier for comment and asked whether he stands by his statement that the methodology was “flawed”.

He was also asked whether it is possible the risk of recurrence could be higher than 1 to 2%.

Prof Cameron did not answer either question directly but said the aim was to create an estimate of possible loss of benefit that was realistic.

He said: “What I meant by ‘not alarming’ referred to the language used to describe the risk estimate, not the risk estimate itself, as that was done as best one could using available clinical data from the pooled data from many, many clinical trials.”

A Scottish Government spokesman said the review group “met over several months, looking at all available evidence and drawing on a wide range of independent expertise”.