Gene test for lung cancer

A new gene test developed by Taipei researchers can predict a lung cancer patient’s  outcome after surgery and the survival time……... Sanjit Bagchi reports.



Lung cancer is the most common cancer affecting people, especially in big cities. It is treatable, depending on the type, stage and severity, but researchers have always been on the lookout for a measure to predict or tailor the treatment of the disease.

Recently, researchers in Taiwan came up with a simple but effective gene test, which can work wonders in the treatment of lung cancer. The study has been published in the New England Journal of Medicine.

Based on the biology, therapy and prognosis, lung cancer is broadly divided into two classes  non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), explains Dr A.K. Pathak and associates at the All India Institute of Medical Sciences (AIIMS), New Delhi. Three types of lung cancer    squamous cell carcinoma, adenocarcinoma and large cell carcinoma    are classified as NSCLC and account for 75-80 per cent of all lung cancer cases.

The clinical profile of lung cancer in India differs from that in the West. Generally, in India, the disease sets in in the fifth or sixth decade of a person’s life, almost 15-20 years earlier than in the West, the AIIMS researchers write in Indian Journal of Chest Diseases and Allied Sciences. Squamous cell carcinoma continues to be the commonest type in India whereas adenocarcinoma is gradually becoming the predominant subtype in the Western world,   they add. Dr Pathak and co-workers also note that  of all lung cancer deaths, 85 per cent are attributable to smoking tobacco, which contains harmful carcinogens.

Hsuan-Yu Chen of the National Taiwan University College of Public Health, Taipei, and his team studied more than 600 genes, which seem to influence survival in NSCLC patients. Of these, they singled out five genes   together called the  5-gene signature   which could significantly predict the patient’s outcome after surgery.

The new 5-gene test indicates if there is a need for chemotherapy. Patients belonging to the high-risk  group have a shorter overall survival (20 months) rate than those in the low-risk group (40 months).   This signature could be useful in stratifying patients according to risk in trials of treatment of the disease,   the researchers write, adding it   may reveal targets for the development of therapy for lung cancer.

After surgical resection, adjuvant chemotherapy is often administered  by chemotherapeutic drugs like cisplatin,   says Prof. Kalyan Dasgupta, former head of the department, chest medicine, Calcutta Medical College, Calcutta. However, it’s difficult to determine which patient is an ideal candidate for chemotherapy, as chemotherapy is helpful in only those who are at a high risk of cancer recurrence.  According to Chen and colleagues, The identification of the 5-gene signature has clinical implications. Cisplatin-based adjuvant chemotherapy is effective in some patients with NSCLC. We propose that patients who have tumours with a high-risk gene signature could benefit from this type of therapy, whereas those with a low-risk gene signature could be spared what may be called unnecessary treatment.

Prof. Dasgupta explains, Unnecessary use of chemotherapy may lead to side effects such as bone marrow suppression, fever, nausea and vomiting. Cost is another important factor.  He adds,  The new gene test can solve this problem. Since it can predict the patient’s surgery outcome and survival, it can determine if he/she needs chemotherapy or not. Treatment can thus be tailored accordingly.

The 5-gene test developed by Chen and co-workers is carried out through a technique known as reverse-transcriptase polymerase chain reaction (RT-PCR). This test needs a small number of genes for analysis, a very small amount of specimen (of the tumour) and yields accurate results.

Dr Bikram Saha, assistant professor of medicine, North Bengal Medical College and Hospital, Darjeeling, says, As the test profiles gene expression, it may be relied on. Moreover, it seems to be acceptable in clinical practice since it does not involve complicated procedures. However, further studies are needed before it can be implemented in general clinical practice.

Source:The Telegraph (Kolkata,India)

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