Knowing that whatever caused a cancer to occur in the first place likely raises the risk of developing another cancer, researchers decided to answer the question, "how often does a second primary lung cancer occur?" And when it happens, what is the prognosis?
It's more than an academic question. For people living with lung cancer, it's good to know if there is any reason to worry - and to be on the lookout for any symptoms suggestive of a new lung cancer. After all, we believe that catching lung cancer as early as possible makes a difference.
In a new study, investigators looked at 2816 lung cancer patients --people with primary lung cancer-- monitoring them to see if they developed a second cancer. Overall, 139 people did develop a second primary cancer (nearly 5%.) As a quick note, in defining these cancers as "second primary cancers" it means that they are new cancers and not a recurrence or spread of the original cancer.
Of the 139 cancers, 69 were non-small cell lung cancers and 9 were small cell lung cancers. The median time between the time the first cancer was diagnosed and the second primary cancer occurred was 72 months.
The results were encouraging. When compared with people diagnosed with a first lung cancer, those people diagnosed with a second primary lung cancer had a better prognosis - even for stage 4 disease. The median survival (the time at which 50% of people have died and 50% are still living) was 57 months for those with a second primary lung cancer vs only 18 months for the control group diagnosed with a first lung cancer.
I'd like to think that having a heightened awareness of the possible symptoms of lung cancer, prompted lung cancer survivors to let their doctors know when those symptoms occurred. Of course, that's only speculation. It could be that the surveillance tests people go through after a diagnosis of lung cancer (those tests that cause fear and "scanxiety") picked up the second cancers sooner than for someone who didn't carry a diagnosis of lung cancer.
The answer to the original question is that 2.8% of the lung cancer patients in this study developed a second primary lung cancer over a period of 5 years. An earlier study found that almost 15% of people treated with surgery for stage 1 lung cancer developed a second primary lung cancer. But even as those numbers are large enough to cause a little fear, it's encouraging to hear that the prognosis for those who have to hear those words "you have cancer" a second time, is better than the first time around.
Reinmuth, N. et al. Characteristics and outcome of patients with second primary lung cancer. The European Respiratory Journal. 2012 Oct 11. (Epub ahead of print).
Rice, D. et al. The risk of second primary tumors after resection of stage 1 nonsmall cell lung cancer. Annals of Thoracic Surgery. 2003. 76(4):1001-7.