New research adds yet another twist to the increasingly complex story surrounding cholesterol and health. It would seem that low cholesterol, which we are told is good for our heart, is not a good sign for people with kidney cancer, as a new study shows it is linked to an increased risk of dying.
Senior investigator Tobias Klatte, an assistant professor at the Medical University of Vienna, Austria, and colleagues write about the findings in the journal BJU International. They suggest cholesterol testing should be considered when monitoring patients with kidney cancer.
There is mounting evidence that the relationship between cholesterol and health and disease is more complex than first thought. For example, in relation to cancer, US researchers have suggested there is an underlying mechanism that affects both cancer and low LDL (so-called "bad") cholesterol. And another study led by a team in Australia suggests cancer spreads with help from bad cholesterol.
Even the division between "good" and "bad" cholesterol is not so clear cut it seems. In January 2014 we learned how HDL or so-called "good" cholesterol has its bad side, when research led by the Cleveland Clinic in the US found a molecular process through which it loses its protective properties and instead contributes to the development of coronary artery disease.
To find out more about the relationship between cholesterol and kidney cancer in particular, Prof. Klatte and colleagues analyzed pre-surgery total blood cholesterol levels in 867 patients with renal cell carcinoma - the most common type of kidney cancer in adults. The patients were then followed for a median of 52 months.
Adding cholesterol levels to risk factors increases accuracy of prognosis
The analysis found the patients who had low blood cholesterol before treatment tended to develop more advanced tumors and their kidney cancer spread more during follow-up.
Patients who had low blood cholesterol before treatment tended to develop more advanced tumors and their kidney cancer spread more during follow-up.
It also found that patients with high levels of cholesterol had a 43% lower risk of dying from their kidney cancer than counterparts with low cholesterol.
And, when they added pre-treatment cholesterol levels to traditional risk factors, the researchers found this increased the accuracy of prognoses.
The study did not investigate the biological reason behind the findings - that is still to be clarified, note the authors. They speculate that perhaps certain components of cholesterol affect the activity of cancer pathways to affect tumor growth and spread.
Whatever the reason, the team suggests cholesterol testing may help doctors monitor and treat patients with kidney cancer.
"As this was a hypothesis-generating study, our findings should be confirmed in independent datasets. If confirmed, patients with low cholesterol may be considered high-risk and may be treated or followed up more aggressively," says Prof. Klatte.
One possible explanation, he adds, is that the tumor is feeding off the cholesterol, and this causes its levels to drop. If that is the case, then cutting off the supply of cholesterol and starving the tumor would be an option to consider in treatment.