THE MOSS REPORTS Newsletter (03/05/06)

[Guest guest]

6 Mar 2006 00:10:24 -0000

" Cancer Decisions " <

THE MOSS REPORTS Newsletter (03/05/06)

 

 

----------------------

Ralph W. Moss, Ph.D. Weekly CancerDecisions.com

Newsletter #226 03/05/06

----------------------

 

 

THE MOSS REPORTS – CANCER DECISIONS NEWSLETTER

 

 

 

AUSSIE ONCOLOGISTS CRITICIZE CHEMOTHERAPY - PART ONE

 

 

An important paper has been published in the journal Clinical

Oncology. This meta-analysis, entitled " The Contribution of Cytotoxic

Chemotherapy to 5-year Survival in Adult Malignancies " set out to

accurately quantify and assess the actual benefit conferred by

chemotherapy in the treatment of adults with the commonest types of

cancer. Although the paper has attracted some attention in Australia,

the native country of the paper's authors, it has been greeted with

complete silence on this side of the world.

 

All three of the paper's authors are oncologists. Lead author

Associate Professor Graeme Morgan is a radiation oncologist at Royal

North Shore Hospital in Sydney; Professor Robyn Ward is a medical

oncologist at University of New South Wales/St. Vincent's Hospital.

The third author, Dr. Michael Barton, is a radiation oncologist and a

member of the Collaboration for Cancer Outcomes Research and

Evaluation, Liverpool Health Service, Sydney. Prof. Ward is also a

member of the Therapeutic Goods Authority of the Australian Federal

Department of Health and Aging, the official body that advises the

Australian government on the suitability and efficacy of drugs to be

listed on the national Pharmaceutical Benefits Schedule (PBS) –

roughly the equivalent of the US Food and Drug Administration.

 

Their meticulous study was based on an analysis of the results of all

the randomized, controlled clinical trials (RCTs) performed in

Australia and the US that reported a statistically significant

increase in 5-year survival due to the use of chemotherapy in adult

malignancies. Survival data were drawn from the Australian cancer

registries and the US National Cancer Institute's Surveillance

Epidemiology and End Results (SEER) registry spanning the period

January 1990 until January 2004.

 

Wherever data were uncertain, the authors deliberately erred on the

side of over-estimating the benefit of chemotherapy. Even so, the

study concluded that overall, chemotherapy contributes just over 2

percent to improved survival in cancer patients.

 

Yet despite the mounting evidence of chemotherapy's lack of

effectiveness in prolonging survival, oncologists continue to present

chemotherapy as a rational and promising approach to cancer treatment.

 

" Some practitioners still remain optimistic that cytotoxic

chemotherapy will significantly improve cancer survival, " the authors

wrote in their introduction. " However, despite the use of new and

expensive single and combination drugs to improve response

rates...there has been little impact from the use of newer regimens "

(Morgan 2005).

 

The Australian authors continued: " ...in lung cancer, the median

survival has increased by only 2 months [during the past 20 years,

ed.] and an overall survival benefit of less than 5 percent has been

achieved in the adjuvant treatment of breast, colon and head and neck

cancers. "

 

The results of the study are summarized in two tables, reproduced

below. Table 1 shows the results for Australian patients; Table 2

shows the results for US patients. The authors point out that the

similarity of the figures for Australia and the US make it very likely

that the recorded benefit of 2.5 percent or less would be mirrored in

other developed countries also. (NB: We apologize for the poor image

quality of these tables.)

 

Table 1

Results for Australian patients

To view a larger image click here or go to:

http://www.cancerdecisions.com/images/Table1.jpg

 

 

 

Table 2

Results for US patients

To view a larger image click here or go to:

http://www.cancerdecisions.com/images/Table2.jpg

 

 

Basically, the authors found that the contribution of chemotherapy to

5-year survival in adults was 2.3 percent in Australia, and 2.1

percent in the USA. They emphasize that, for reasons explained in

detail in the study, these figures " should be regarded as the upper

limit of effectiveness " (i.e., they are an optimistic rather than a

pessimistic estimate).

 

Understanding Relative Risk

 

 

How is it possible that patients are routinely offered chemotherapy

when the benefits to be gained by such an approach are generally so

small? In their discussion, the authors address this crucial question

and cite the tendency on the part of the medical profession to present

the benefits of chemotherapy in statistical terms that, while

technically accurate, are seldom clearly understood by patients.

 

For example, oncologists frequently express the benefits of

chemotherapy in terms of what is called " relative risk " rather than

giving a straight assessment of the likely impact on overall survival.

Relative risk is a statistical means of expressing the benefit of

receiving a medical intervention in a way that, while technically

accurate, has the effect of making the intervention look considerably

more beneficial than it truly is. If receiving a treatment causes a

patient's risk to drop from 4 percent to 2 percent, this can be

expressed as a decrease in relative risk of 50 percent. On face value

that sounds good. But another, equally valid way of expressing this is

to say that it offers a 2 percent reduction in absolute risk, which is

less likely to convince patients to take the treatment.

 

It is not only patients who are misled by the overuse of relative risk

in reporting the results of medical interventions. Several studies

have shown that physicians are also frequently beguiled by this kind

of statistical sleight of hand. According to one such study, published

in the British Medical Journal, physicians' views of the effectiveness

of drugs, and their decision to prescribe such drugs, was

significantly influenced by the way in which clinical trials of these

drugs were reported. When results were expressed as a relative risk

reduction, physicians believed the drugs were more effective and were

strongly more inclined to prescribe than they were when the identical

results were expressed as an absolute risk reduction (Bucher 1994).

 

Another study, published in the Journal of Clinical Oncology,

demonstrated that the way in which survival benefits are presented

specifically influenced the decision of medical professionals to

recommend chemotherapy. Since 80 percent of patients chose what their

oncologist recommends, the way in which the oncologist perceives and

conveys the benefits of treatment is of vital importance. This study

showed that when physicians are given relative risk reduction figures

for a chemotherapy regimen, they are more likely to recommend it to

their patients than when they are given the mathematically identical

information expressed as an absolute risk reduction (Chao 2003).

 

The way that medical information is reported in the professional

literature therefore clearly has an important influence on the

treatment recommendations oncologists make. A drug that can be said,

for example, to reduce cancer recurrence by 50 percent, is likely to

get the attention and respect of oncologists and patients alike, even

though the absolute risk may only be a small one - perhaps only 2 or 3

percent - and the reduction in absolute risk commensurately small.

 

 

TO BE CONCLUDED, WITH REFERENCES, NEXT WEEK

 

 

 

Signature

--Ralph W. Moss, Ph.D.