Scientists identify genetic markers for aggressive lung cancer
US scientists have identified genetic alternations in early-stage lung tumours that could be used to predict whether a patient's cancer is likely to recur, according to new research published in the New England Journal of Medicine.
The discovery could be used to determine whether an individual is at particularly high-risk of recurrence and should be treated more aggressively with chemotherapy after surgery.
Researchers at Johns Hopkins Kimmel Cancer Centre examined markers on the DNA of tumour cells called methyl groups, which are known to switch certain genes on or off. Disruption of the patterns of methyl groups on a cell's DNA can lead to abnormal protein production that can, in turn, lead to cancer.
The researchers analysed the methylation patterns in more than 700 tumour and lymph node samples from 167 early-stage, non-small cell lung cancer patients. Of those patients, 51 experienced a recurrence of their cancer within 40 months while 116 remained cancer-free.
They found that four genes linked to the development of lung cancer - p16, H-cadherin, APC and RASSFIA - showed higher levels of methylation in patients whose cancer recurred and, for many of the genes, the amount of methyl groups was twice as high in samples from patients with recurrent disease.
Dr Malcolm Brock, associate professor of surgery at Johns Hopkins, said: "The DNA evidence we see for many of the recurring cases suggests it may be wise if our work is confirmed to reclassify such cancers as advanced disease instead of early stage.
"While there may be no trace of cancer that we can spot after surgery with a microscope, the DNA evidence from these tumours may have been left at the scene, especially in lymph nodes."
The study also identified 11 patients who had high levels of methylation in both p16 and H-cadherin in tumour tissue and a remote lymph node. In eight of these patients, lung cancer had returned within one year, while the remaining three patients had experienced a recurrence of their cancer within 30 months.
The research is ongoing and Dr James Herman, a medical oncologist at Kimmel Cancer Centre, also raised the possibility of therapies that strip off these methyl groups.