Background of Small Cell Lung Cancer

Kathryn Gold, MD: Welcome to this OncLive NewsNetwork® presentation, broadcasting virtually from across the country. My name is Kathryn Gold, I’m a physician in medical oncology, specializing in thoracic and head and neck cancers here at UCSD [University of California, San Diego] Morris Cancer Center. Today’s discussion will be focused on immuno-oncology [I/O] in combination with chemotherapy for the first-line treatment of extensive-stage small cell lung cancer. Joining me today in this discussion are my colleagues, Dr Konstantinos Leventakos from the Mayo Clinic in Rochester, Minnesota, and Dr Taofeek Owonikoko from Winship Cancer Institute at Emory University in Atlanta, Georgia.

During the next 60 minutes, we’re going to navigate through the new role of I/O therapy in combination with chemotherapy for first-line treatment of extensive-stage small cell lung cancer and the questions surrounding how to use this approach in clinical practice. Let’s dive in and get started with our first topic.

First, we’ll be covering some of the characteristics of small cell lung cancer and how it differs from non–small cell lung cancer. Could you two discuss a little bit about how often you encounter patients with small cell lung cancer in your practice, and how do these patients typically present? Taofeek, I’ll let you take the lead on this one.

Taofeek K. Owonikoko, MD, PhD: Thanks for joining us from across the country. As we know, lung cancer is the most common cancer type that we deal with in the United States; worldwide, it’s still a major disease burden. The majority of our patients will have the non–small cell category, but small cell is not to be underestimated. About 13% to 15% of our patients with lung cancer will have the small cell variety, and if you think about the diagnosis of about 240,000 a year in the United States, that’s somewhere on the order of 30,000 to 40,000 patients with small cell lung cancer. These are not rare cases; we all have them in our practices, depending on where we’re located in the country. I practice in the Southern Belt—what we call the Tobacco Belt—where a lot of our patients will have much more advanced stages of lung cancer in general, but the proportion of patients with small cell may be higher than what you’d see on the West Coast, or maybe even in the Midwest to some degree.

For my thoracic-focused practice, I would say about 20% of it is patients with small cell lung cancer. Of this 20%, the majority of patients are coming in from outside facilities following their frontline treatment for either salvage therapy or participation in clinical trials. In terms of the distribution by stage, I think this cuts across everywhere we practice. The majority of our patients present very late. I don’t think it’s necessarily because of ignoring the symptoms. I think it’s because small cell, as we know, has a very rapid growth rate; the biology is very aggressive. By the time the patient is diagnosed, they’re already beyond the stage where we can start talking about cure. Unfortunately, 60% to 70% of our patients are incurable when they present with extensive-stage disease. One-third of them will present with limited-stage disease, and when we are lucky at that stage, we can at least shoot for a cure, which we know is not achievable for every patient. With the combination of chemotherapy and radiation that we use, we can anticipate about one-fourth of patients with limited stage will achieve durable control of disease, which may eventually turn into a cure.

Kathryn Gold, MD: Konstans, how do you see people presenting to your clinic with small cell?

Konstantinos Leventakos, MD, PhD: This is a very common situation, as Taofeek said, because lung cancer is the most commonly seen cancer in the United States; 15% of patients with lung cancer who have small cell is still a good amount of patients. Most of the patients present with symptoms that would either be generalized, where the primary care doctor gave the CT scan and found a mass that was biopsied and discovered to be small cell lung cancer, or any findings, including patients who were identified to have small cell through screening. This is new, that we might be seeing a little more early-stage small cell lung cancer because of screening. I agree with Taofeek; with the modalities that we are using, this is the time that we may be talking about a cure. In our center, we have a big population. We are a primary cancer center, so we see first diagnoses of small cell; we also have a lot of second opinions for patients who have already had first-line treatment.

Kathryn Gold, MD: What are some of the risk factors that you observe in your patient population for small cell?

Konstantinos Leventakos, MD, PhD: I think that we all agree that the main risk factor is smoking, and the risk of small cell lung cancer increases with the amount of smoking that someone has done all their lives. We see it also in ex-smokers, even though we always advise to quit smoking. It is important to say that with the policies to restrict smoking, we have seen the numbers of small cell coming down. We have seen more of an increase in women rather than in men, and that probably shows all the physiology of smoking and smoking-related cancers.

Transcript Edited for Clarity