Dr. Purvish Parikh writes about the approach for oligometastatic disease in lung cancer among Indian patients, suggesting that it may not always be necessary to go by the general applicability of recommendations while planning treatment and management.

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The average life expectancy of metastatic (stage IV) lung cancer has increased from 8 months to more than 2 years. Earlier, only 10% of lung cancer patients were diagnosed early enough to be offered surgery with curative intent. With better understanding of the biology, more specific delineation of patients with stage III disease and availability of more effective therapy, another 10% now have the opportunity to be treated with curative intent. Adjuvant chemotherapy adds another 5% benefit.

So the limits are now being pushed to define another subgroup that could be cured- patients with oligometastatic disease. The hypothesis began on the concept that patients with few metastasis in specific organs can still be managed in a manner that can keep them alive for five years or more.

Over the last decade, several publications have supported this thinking. Do they have a less aggressive tumor that tends to remain stable for a longer period of time? Could local ablative therapy interrupt the metastatic cascade and thus offer opportunity to cure?

The first challenge is to define what constitutes oligometastatic disease in lung cancer. Among the various criteria mentioned are:

1. Single metastasis in any one organ (tumour-node-metastasis 8 [TNM8])
2. 1-3 metastases (European Society for Medical Oncology [ESMO])
3. < 3 metastases (including mediastinal nodes [MLN]) after systemic treatment
4. Between 3 and 5 metastases (criteria used in ongoing clinical trials)

Keeping in mind that about 7% of all patients with lung cancer will fulfill the ESMO criteria mentioned above, let us estimate how many Indians will have oligometastatic lung cancer this year. Indian Council for Medical Research projects 17 lakh new cancer patients in our country in 2020. We have a 12% incidence of lung cancer, making the number 2.04 lakhs. And 7% of these make it 1428 per year. So we could save the additional lives of almost 1500 lung cancer patients if they are offered a potentially curative approach.

In one study by Ni Y et al. published in the Journal of Cancer Research Clinical Oncology in 2019, a total of 86 EGFR-mutated non-small cell lung cancer patients presented in stage IIIB or IV and having extracranial oligometastasis.

• The 52/86 received only oral tyrosine kinase inhibitors (TKIs) till progressive disease recorded a median overall survival (OS) of 22.7 months.
• The remaining 34/86 who also received local consolidative therapy and achieved a median OS of 34.8 months. This shows us the value of local ablation even in patients with very advanced lung cancer.

Other studies have also confirmed such benefit. We have earlier studied the perception amongst 166 oncologists regarding oligometastatic lung cancer. Surprisingly, the real world experience was different from guidelines. Based on the site and type of oligometastasis, oncologists treated their patients differently from published recommendations. We were able to divide this into three categories:

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

The author, Dr. Purvish Parikh is the Group Oncology Director & Professor of Medical Oncology at Shalby Cancer & Research Institute, Ahmedabad.