(RxWiki News) Cancer remains primarily a disease of the elderly. Aging also increases the incidence of other diseases such as heart disease and diabetes. A new study looked at how other health issues impact cancer survival.
After reviewing more than 2,500 studies, Danish researchers found that cancer patients with other illnesses (comorbidities) tended to have poorer survival rates than cancer patients who didn’t have other health issues.
The authors concluded that a number of factors contributed to these poorer survival rates, but that many specific questions regarding how comorbidity affects cancer survival remain unanswered.
"Make sure your doctor knows about all your health issues."
Mette Søgaard, PhD, a researcher in the Clinical Epidemiological Department or Aarhus University and Aarhus University Hospital in Aarhus, Denmark, reviewed 2,692 studies relating to comorbidity and survival among patients with breast, colon and lung cancers.
In the study's introduction, the researchers wrote, “In recent decades, 5-year survival rates have improved among cancer patients without comorbidity, but not among patients with severe comorbidity.”
The researchers found that as many as 68 percent of colon cancer patients had other illnesses, as did 20 to 35 percent of breast cancer patients and up to 81 percent of lung cancer patients.
Studies that included five to seven years of follow-up found that, compared to patients with no other diseases, breast cancer patients with any comorbidity had up to a nearly six-fold (5.8-fold) higher death rate.
Colon cancer patients with comorbidity had a 1.2- to 4.8-fold higher five-year mortality (death) rate than did colon cancer patients who weren’t also battling other diseases.
Lung cancer patients with comorbidity had a 1.1 to 1.5 times higher death rate than patients with no comorbidity.
How much comorbidity impacted survival depended on the co-existing disease and the particular type of cancer. But the overall picture was the same: other diseases had a negative impact on both one- and five-year survival, the researchers discovered.
“In general, comorbidity does not appear to be associated with more aggressive types of cancer or other differences in tumor biology. Presence of specific severe comorbidities or psychiatric disorders were found to be associated with delayed cancer diagnosis in some studies, while chronic diseases requiring regular medical visits were associated with earlier cancer detection in others,” the researchers wrote.
One of the study’s authors, Henrik Toft Sørensen, PhD, DMSc, placed unhealthy lifestyle factors (smoking, excessive alcohol consumption and being overweight) among the reasons for the poor survival rates.
In addition, patients with other illnesses have higher complication rates from cancer treatments, according to the researchers.
According to the authors, additional research is needed to “... elucidate whether comorbidity in general or only specific diseases or disease combinations are associated with poorer survival.”
And comorbidity may affect treatment choices, resulting in too much, too little or incomplete treatment, the authors suggested.
This study was published in the November issue of the journal Cancer Epidemiology.
The Danish Cancer Society funded the work, and no conflicts of interest were disclosed.