Use of the TNM Staging System in SCLC


Charles Rudin, MD, PhD, explains the prognostic staging systems used for small cell lung cancer.

Charu Aggarwal, MD, MPH: Charlie, how do you use or what staging system do you use for current management of your patients. Could you talk to us about different staging systems and what's your preferred?

Charles Rudin, MD, PhD: The International Association for the Study of Lung Cancer has put out a statement, and firmly believes, that we should stage small cell lung cancer as we do every other lung cancer that is using the TNM [tumor, nodes, metastastes] staging system. And in fact, those stages are prognostic for small cell lung cancer. From a practical perspective. Most of us favor just separating small cell into what we call limited stage and extensive stage disease. That's a very practical definition, and one that dictates the approach to therapy. Limited stage disease is disease that's combined to one side of the chest one hemithorax, and that can be generally encompassed within a radiation port that the radiation oncologist feels that they can adequately treat effectively to get good local control. For those patients who have limited stage disease, the standard of care would be a combination of radiation and chemotherapy with the radiation really for local control - chemotherapy really has 2 functions there. One to synergize with the radiation - it's a radio enhancer makes the radiation more effective, and probably more importantly actually gives systemic control treating the rest of the body for microscopic disease, which is probably present in almost all patients who have a diagnosis of limited stage small cell lung cancer. Extensive stage is just the opposite, that is, it's anybody who does not have limited stage disease whose disease has progressed to the point where they no longer can be effectively encompassed within a radiation port. Frequent sites of metastasis would be the contralateral lung. Brain is very common in small cell lung cancer patients, bone liver, and adrenal.

Charu Aggarwal, MD, MPH: And you outlined the differences between limited stage and extensive stage. We tend to use these in practice also more frequently because they have such clear-cut sort of categories in terms of what treatments we recommend, but also prognostic categories. We know that extensive stage - patients with extensive stage small cell lung cancer, we can adequately define what their overall survival would be, what kind of clinical trials they would go fall into. Vivek I would like to ask you, are there any current biomarkers that you're using or interested in for patients with small cell lung cancer?

Vivek Subbiah, MD: Absolutely. Thank you so much for the great question. As Jared said, under the light microscope, they all look as small round blue cell tumors and they do specific stains to showcase and also confirm that it is small cell lung cancer. And in the next in sequencing era we have extensively studied in many academic centers the biology of small cell lung cancer inactivation of RB1 and TP53 gene coded by the retinoblastoma gene and the P53 is, are near a ubiquitous events in small cell lung cancer. Now beyond this 4 different molecular classifications or subtypes have been described again, they are of academic interest, mainly the SCLC type A small cell lung cancer type N type P and Y based on the expression of transcription factors. Also, we see mic amplification and also not mutations, but again, these are to date of academic interest for us. And they don't guide us clinically in terms of how we treat patients that present to us in our clinic. So the short answer is we are working on it and no.

Jared Weiss, MD: They give us hope though, that we're starting to understand the biology and subtype. And there's a shared optimism amongst many in the field that they're a hint of what's to come, even if, if not ready for clinical practice yet.

Transcript edited for clarity.

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