For nearly forty years, small cell lung cancer remained essentially unchanged. Platinum-etoposide served as the cornerstone of therapy, producing rapid responses that were often followed by equally rapid relapses, and few effective subsequent options. However, the perseverance of the tenacious thoracic research community has finally moved the field forward.

For medical oncologists who care for patients with small cell lung cancer, understanding this evolving therapeutic landscape is important to ensure that patients receive the most effective and appropriate care possible.

Smoking Cessation: If This Were a Drug, We Would All Be Using It

Before discussing recent FDA approvals, it is worth pausing to consider an intervention that costs nothing, requires only a few minutes in clinic, and may have a greater impact on outcomes than many therapies we routinely prescribe-smoking cessation counseling.

Small cell lung cancer is overwhelmingly a disease of tobacco exposure, with more than 95% of cases occurring in current or former smokers. Importantly, smoking cessation remains beneficial even after a cancer diagnosis. Quitting smoking at the time of diagnosis has been associated with a 31% reduction in mortality among patients with early-stage lung cancer and a 36% reduction in mortality among those with advanced-stage disease. If a new drug produced survival benefits of that magnitude, we would prescribe it without hesitation.

However, the reality is this simple, essential intervention is very often forgotten in busy clinics. In an era increasingly defined by novel agents, it is easy to overlook the fundamentals. Yet smoking cessation remains one of the most effective interventions available to improve outcomes for patients with small cell lung cancer. Patients also may feel hesitant, as many question the need to quit if they already have cancer and “the damage is already done.” It is very important for the care team members to reiterate to our patients that quitting smoking at the time of diagnosis meaningfully improves survival as noted above, may reduce treatment-related toxicity, improve quality of life, and decrease the risk of additional smoking-related illnesses.

Clinical guidelines reflect the strength of this evidence. The National Comprehensive Cancer Network (NCCN) recommends that smoking cessation counseling and evidence-based treatment be offered at a patient's very first oncology visit. The Commission on Cancer directs all accredited cancer centers to perform a tobacco use assessment and cessation intervention as a quality benchmark under Standard 5.9.

Limited Stage SCLC: Surgery, Chemotherapy, and Radiation

Approximately 30% of patients with small cell lung cancer (SCLC) present with limited-stage disease at diagnosis. The truly node-negative (N0) patient is rare, perhaps 5% of all SCLC, and is almost always discovered incidentally on imaging done for another reason. N0 status needs rigorous confirmation with PET as well as mediastinal staging. If confirmed, surgery followed by platinum-based chemotherapy is preferred regardless of tumor size. There is no lesion small enough to omit systemic chemotherapy after resection in SCLC—a 1 mm incidentally discovered nodule still warrants adjuvant chemotherapy once resected.

If intraoperative staging reveals mediastinal lymph node involvement, post-operative concurrent chemoradiation is preferred. Depending on clinical factors, chemotherapy followed by consideration of post-operative radiation could be an alternative. When negative surgical margins could not be achieved, re-resection is pursued if feasible; otherwise, again chemoradiation is the preferred approach.

For patients who are not surgical candidates or who have extensive nodal involvement, concurrent chemoradiation followed by immunotherapy is the standard approach. The standard radiation dose is 45 Gy in twice-daily fractionation, though 66 Gy in once-daily fractionation is an accepted alternative supported by the CONVERT trial. For community settings where twice-daily radiation is logistically difficult, once-daily dosing is a reasonable approach.

The PCI Question: Moving Toward Surveillance

Prophylactic cranial irradiation has a long history in SCLC. It reduces brain metastases and historically showed an overall survival benefit. However, all trials showing survival benefit predate modern MRI surveillance.

The landscape shifted with the Japanese JCOG 0504 study, published in 2017, which compared PCI to active MRI surveillance in extensive stage patients who had responded to chemotherapy. There was no survival benefit to PCI when compared to active surveillance.

With modern MRI surveillance performed every two to three months, brain metastases can often be detected at an early stage, very often allowing lesions to be treated with stereotactic radiosurgery (SRS) as needed. Given the potential neurocognitive and quality-of-life consequences of whole-brain irradiation, the decision to pursue prophylactic cranial irradiation (PCI) versus MRI surveillance should be individualized and guided by shared decision-making. Ongoing studies, including the Phase III MAVERICK trial, aim to address this question more definitively, but in the meantime, many clinicians have increasingly adopted a strategy of close MRI surveillance with selective use of SRS for patients who develop brain metastases, when preservation of cognitive function and quality of life is a priority.

Durvalumab Consolidation After Chemoradiation in Limited Stage

The ADRIATIC trial demonstrated that two years of durvalumab consolidation following concurrent chemoradiation for limited-stage SCLC significantly improves outcomes. Among patients whose disease had not progressed after definitive chemoradiation, median overall survival increased from 33.4 months to 55.9 months, while median progression-free survival improved from 9.2 months to 16.6 months with durvalumab compared with placebo. These findings established durvalumab consolidation as a new standard of care and represent the first major advance in the treatment of limited-stage SCLC in decades. Much as the PACIFIC trial transformed the management of unresectable stage III NSCLC, ADRIATIC validated consolidation immunotherapy after definitive chemoradiation and ushered in a new treatment paradigm for limited-stage SCLC.It is important to note that NRG-LU005, which used atezolizumab concurrently with cycle 2 of chemotherapy along with radiation, did not show benefit.

Therefore, the accepted standard remains using durvalumab consolidation post-chemoradiation as the evidence-supported approach per the ADRIATIC trial

Extensive Stage SCLC: What Immunotherapy Has Changed

The incorporation of checkpoint inhibitors into first-line treatment for extensive-stage SCLC has produced consistent, if still modest, gains. In CASPIAN, durvalumab plus platinum-etoposide yielded a 3-year overall survival rate of 17.6%, compared with 5.8% with chemotherapy alone. In IMpower133/IMbrella A, long-term follow-up of atezolizumab plus carboplatin-etoposide showed that approximately 12% of patients were alive at five years. One in ten patients with extensive-stage SCLC surviving five years was not something we could achieve before the immunotherapy era.

Admittedly, most patients still progress and die from this disease. Still, there is now an unprecedented and meaningful tail on the survival curve.

Second-Line SCLC: Tarlatamab

The most important second-line development in recent years is tarlatamab, a bispecific T-cell engager that bridges CD3 on T cells to DLL3 on tumor cells. DLL3 is expressed on the surface of SCLC cells and largely absent on normal tissue, making it an attractive target. The mechanism works by physically bringing T cells into contact with tumor cells that would otherwise evade immune recognition.

The DeLLphi-304 trial, published in the New England Journal of Medicine in 2024, established tarlatamab as the preferred second-line therapy in SCLC, demonstrating both progression-free survival and overall survival advantages over topotecan and irinotecan, our usual second line drugs in the pre-Tarlatamab era,.

The most concerning toxicities to anticipate are cytokine release syndrome (CRS) and Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS).These can be life threatening, and monitoring protocols are essential. The FDA-approved prescribing information includes specific management guidelines. For most patients, the toxicity profile is manageable with preparation and awareness.

Where the Field Is Going

The SCLC pipeline is more active than it has been in decades, with several emerging targets being evaluated in combination with first-line immunotherapy, maintenance strategies, and relapsed disease. B7-H3 is a particularly active target, with B7-H3–directed antibody–drug conjugates such as ifinatamab deruxtecan showing promising activity in previously treated extensive-stage SCLC. TROP2-directed approaches, including sacituzumab govitecan, have also shown preliminary activity, while CD56, a classic SCLC surface marker, remains under investigation as an ADC target.

Lurbinectedin remains an FDA-approved option after platinum-based therapy and, more recently, was approved in combination with atezolizumab as first-line maintenance for patients with extensive-stage SCLC whose disease has not progressed after atezolizumab, carboplatin, and etoposide induction. In sequencing decisions, tarlatamab has emerged as a preferred second-line option on the strength of randomized overall survival data, with lurbinectedin remaining an alternative in selected clinical situations.

For Patients

If you have been diagnosed with small cell lung cancer, there is reason for cautious optimism. The treatment options available today are meaningfully better than they were just five to ten years ago. Immunotherapy combined with chemotherapy has helped some patients with extensive-stage disease live longer than was previously possible, including a small but growing group of long-term survivors.

In addition, a newer treatment called tarlatamab has been approved for patients whose cancer has progressed after chemotherapy. Tarlatamab works differently from both traditional chemotherapy and standard immunotherapy and has provided meaningful responses for some patients with relapsed disease.

Clinical trials remain critically important in small cell lung cancer and may provide access to promising new therapies that are not yet widely available. Ask your oncologist whether a clinical trial may be appropriate for you.

Finally, if you currently smoke, consider accepting help to quit. Even after a diagnosis of lung cancer, smoking cessation can improve treatment outcomes, reduce complications, and help you live longer. Your oncology team can connect you with effective medications, counseling, and other resources to support you through the process.

Key Takeaways

Smoking cessation at diagnosis reduces SCLC mortality by 31–36%; counseling at every visit is now a Commission on Cancer standard.
Truly N0 limited stage SCLC warrants surgery plus chemotherapy regardless of tumor size; there is no lesion small enough to omit systemic therapy.
Concurrent chemoradiation is standard for limited stage; 45 Gy BID or 66 Gy once daily are both acceptable.
Durvalumab consolidation post-chemoradiation improves outcomes in limited stage SCLC
Active MRI surveillance is increasingly replacing PCI; individualized discussion with patients is appropriate.
First-line immunotherapy plus chemotherapy has produced 3-year OS of approximately 18% and 5-year OS of approximately 12% in extensive stage
Tarlatamab (DLL3-directed BiTE, DeLLphi-304) is the FDA-approved preferred second-line therapy with demonstrated OS benefit over topotecan.

References

IMpower133. Atezolizumab plus carboplatin/etoposide in extensive stage SCLC. New England Journal of Medicine, 2018; 5-year update 2023.
CASPIAN trial. Durvalumab plus platinum-etoposide in extensive stage SCLC. Lancet, 2019; 3-year update 2022.
ADRIATIC trial. Durvalumab consolidation after chemoradiation in limited stage SCLC. New England Journal of Medicine, 2024.
DeLLphi-304. Tarlatamab vs topotecan/irinotecan in previously treated SCLC. New England Journal of Medicine, 2024. FDA approval 2024.
Takahashi T, et al. (JCOG 0504). PCI versus surveillance MRI in SCLC. Journal of Clinical Oncology, 2017.