Heavy smokers are susceptible to a type of lung cancer that is hard to treat – arthritis of the knee could be the first sign of this type of cancer, according to a report published in the Annals of the Rheumatic Diseases.

In the study, the researchers looked at the case notes of all patients who suffered from rheumatic disorders who were diagnosed at one tertiary referral center over a period of six years. Over 6,599 new patients attended the clinic during 2000-2005. 296 (4.4%) of them had monoarthritis of the knee – just one knee had inflammation. Just under 2% of them had undiagnosed (at that time) non-small cell lung cancer – they were all middle-aged men who had been heavy smokers for most of their lives.

Once their lung cancer had been operated on and the cancerous tissue removed, their knee symptoms subsided.

Non-small cell lung cancer is associated with other conditions with abnormal growths (20% of cases). In about 20% of cases it spreads to the bones.

The authors point out that it has not yet been linked to arthritis.

Effective treatment for non-small cell lung cancer is only really effective if it is caught early. In over 50% of cases the disease is already advanced when it is diagnosed.

The authors stress that features that may act as early-warning signs are especially important.

“Isolated knee monoarthritis heralding resectable non-small cell lung cancer: a paraneoplastic syndrome not previously described”
Fabrizio Cantini, Laura Niccoli, Carlotta Nannini, Daniela Chindamo, Michele Bertoni, Emanuele Cassarà and Carlo Salvarani
Online First Ann Rheum Dis 2007; doi: 10.1136/ard.2007.075333
Click here to view abstract online

Written by: Christian Nordqvist