Karolinksa report under scrutiny from Professor Michael Coleman for using flawed methods to reach flawed conclusions...
19 Sep 2007
Prof. Michael Coleman, a Professor of epidemiology and vital statistics at the London School of Hygiene and Tropical Medicine, criticises the new Karolinska report that it, "uses flawed methods to reach flawed conclusions about the link between cancer drug 'vintage' and cancer survival in European countries."
The first Karolinksa report, published in 2005, concluded that the 'more cancer drugs there are on the market in a country, and the more quickly they are licensed for the market, the higher is that country's cancer survival rate'
The second Karolinska report - far reaching a global audience and published as a peer reviewed supplement in the pages of the Annals of Oncology - the official journal of the European Society of Medical Oncology (ESMO), has been assessed and disparaged by Professor Coleman.
The focus for Professor Coleman's disparagement is on the European analysis of cancer survival as a function of drug 'vintage' (the year that the cancer drug was first launched). Coleman compared the Karolinska reports analysis of cancer survival rates to the more practiced method of calculating cancer survival rates, which is to draw the calculations from the cancer patients' actual duration of survival. Coleman explains that in this second report, the cancer survival rates were calculated by dividing the total of number of, "five year survivors by the total number of cancer patients diagnosed each year - a tactic which ignores both year-to-year changes in those numbers and the wide differences in cancer survival by age, sex and cancer type." Coleman compares the estimated survival rates presented in the Karolinska report for France, with five year, relative survival rates estimated by cancer specialists in France.
"The cancer survival estimates in the Karolinksa report are wrong. For France, the report gives 5-year survival for all cancers combined as 71% for women and 53% for men, the highest of the EU countries examined. Cancer survival specialists in France recently estimated 5-year relative survival for all cancers combined as 63% for women and 44% for men - some 8-9% below the values in the Karolinska report."
He also points out that survival data in the report came from the EUROCARE-3 study which related to patients diagnosed with cancer between 1999 and 1994. This means that the data on drug usage around 2003 was ten years out of date for the cancer patients with whom the survival data was modelled on.
With EUROCARE-4 not even published yet, which includes more recent data on survival in Europe, Coleman points out that, "despite noting that cancer drug expenditure quadrupled during the period 1995-2005, and half the cancer drug expenditure in 2005 was for drugs launched during that period, the authors again sidestep this issue by claiming that national cancer drug uptake in 2003 is still likely to be representative of uptake in or around 1993."
Coleman includes in his commentary the impact of chemotherapy on cancer survival, and the Karolinksa reports perspective on this. The report assessed the impact of cancer drugs on survival in Australia and the USA where clinical trials reported chemotherapy benefiting survival in one of 22 varying adult malignancies. This, "suggests that the overall contribution of chemotherapy to survival up to five years after diagnosis may be about 2%."
Putting patients at the core of the commentary, Coleman states that, "No-one wants cancer patients to be denied access to drugs (or any other treatment) than may save or prolong their lives." He says in his strategy, that, "An industry seeking to purchase 'independent' academic corroboration of an industry-funded study on drug access and cancer outcome, in order to support the launch of an industry-funded campaign in which wider use of the industry's products would be expected to figure highly, might expect to be viewed with some concern, if not by marketing executives, t