Antonio Lisani and Albert Huang
are the same age; both 51-year-olds have prostate cancer
at the same stage, and both enjoy Beethoven's Fifth. According
to current systems of cancer classification, which say
a lot more about the tumour than about the patient carrying
it, Antonio and Albert might share the same prognosis.
According to an article in the May 26 issue of the Journal
of the American Medical Association, other conditions,
such as Antonio's diabetes, would help flesh out this
one-dimensional picture and lead to more accurate prognoses.
Dr Jay F Piccirillo of Washington
University School of Medicine in St Louis and colleagues,
set out to see how information about patients' comorbidities
could help predict cancer prognosis.
"Comorbidity is generally not considered in the
design of cancer data sets or included in observational
research," say the authors. "In many cases,
comorbid health problems may be so severe as to impact
directly on survival or prohibit the use of preferred
antineoplastic therapies."
Over the course of six years, the researchers prospectively
followed a cohort of 17,712 patients diagnosed with
one of the following cancers: prostate, lung, breast,
digestive system, gynecological, urinary system, or
head and neck. They used the Adult Comorbidity Evaluation
27 (ACE-27) index to label comorbidity of a particular
disease as mild, moderate or severe, according to how
badly the affected organ was attacked by illness. Patients
were assigned an overall comorbidity score based on
the highest ranked single ailment, or were given an
overall severe comorbidity score if they had the bad
luck to suffer from two or more moderate ailments in
different organ systems.
Hypertension was the most frequent comorbid ailment
found, followed by previous cancer and diabetes mellitus.
The more severe the comorbidity, the more hazardous
it seemed to be for patients. For instance, 78% of people
in the no comorbidity group survived three years, but
only 54% in the severe comorbidity group lasted as long.
On the other hand, prognoses for deadlier cancers were
less likely to be strongly influenced by comorbidities.
Thus, in prostate cancer, severely comorbid patients
showed an all-cause mortality hazard ratio 9.21 times
higher than patients without comorbidity. Conversely,
in non-small-cell lung cancer the hazard ratio was only
1.48 times greater in the severe group. Comorbidity
was also found to influence tumour recurrence. The odds
ratios for developing recurrence were 1.18 for mild,
1.37 for moderate and 1.54 for severe comorbidity.
The authors believe that a comorbid condition could
impact survival in various ways. Obviously, the comorbid
condition itself could kill the patient outright. It
could also be a physiological burden, weakening the
body's natural defences. Finally, it could influence
treatment decisions, as in the case of a patient whose
overall health rules out surgery.
Many cancer studies have ignored comorbid conditions,
or excluded patients suffering from them. Yet in this
patient sample, more than half the patients had a disease
other than their cancer. If research is to reflect real-world
conditions, say the authors, such patients should be
included more often.
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