What Is the Risk of a Second Cancer After Early-Stage Lung Cancer?

With the increasing use of screening methods, more patients are being diagnosed with lung cancer at an early stage, and treatments given at these stages are producing better outcomes. Surgery plays an important role in treating early-stage lung cancer. In particular, T1aN0 lung cancer represents a critical stage in this effort. According to the 8th edition of the tumor, node, metastasis (TNM) classification, cancers at this stage are tumors smaller than 1 cm that have not spread to the lymph nodes or other organs. Treatment at this stage may involve lobectomy (lobar resection) or a smaller operation called sublobar resection (partial lobectomy). However, the effect of each of these treatment methods on the risk of a second primary lung cancer remains a subject of interest.

Second primary lung cancer, in a patient previously diagnosed with another lung cancer, refers to the development of a new and independent cancer. This new cancer may differ genetically and histologically from the previous cancer and may develop in the same lung or the other lung. A second primary lung cancer may appear after the first cancer has been treated and may require a different treatment approach.

T1aN0 Lung Cancer and Its Treatment

T1aN0 lung cancer is usually diagnosed during lung cancer screening using low-dose computed tomography and can be treated successfully with surgery. At this stage, choosing the most appropriate surgical method for the patient, taking into account the size and spread of the cancer, is a critical decision. Lobectomy and sublobar resection are the two main surgical methods frequently preferred at this stage. However, how these operations affect the risk of a second primary lung cancer is a focus of research in this field.

Key Findings of the Study

Journal of Clinical Oncology  published this study reported by Dr. Thomas Stinchcombe and colleagues, which includes analyses from the phase III Cancer and Leukemia Group B 140503/Alliance trial. Between 2007 and 2017, 697 patients diagnosed with T1aN0 non–small-cell lung cancer (NSCLC) were randomized to undergo lobectomy (357 patients) or sublobar resection (340 patients). The study showed that sublobar resection was noninferior to lobectomy (its outcomes were no worse) in terms of disease-free survival.

• Follow-Up Duration and Screening: Patients underwent annual computed tomography (CT) scans for 5 years after surgery. The median follow-up duration was 7 years.
• Annual Rates of Second Primary Lung Cancer:
  • Overall, 3.4% of patients developed a second primary lung cancer each year (confidence interval [CI]: 2.9%–4.1%).
  • In the sublobar resection group, this rate was 3.8% per year (CI: 2.9%–4.9%).
  • In the lobar resection group, this rate was 3.1% per year (CI: 2.4%–4.1%).
• 5-Year Cumulative Incidence of Second Primary Lung Cancer:
  • In the entire patient population, the rate of developing a second primary lung cancer within 5 years was 15.9% (CI: 12.9%–18.9%).
  • In patients who underwent sublobar resection, this rate was 17.2% (CI: 12.7%–21.5%).
  • In patients who underwent lobar resection, this rate was 14.7% (CI: 10.6%–18.7%).

In conclusion, the observed rates of second primary lung cancer appear clinically important, and these findings raise questions about the optimal frequency, duration, and type of screening imaging. This study provides important insights into the side effects and long-term outcomes of surgical approaches to lung cancer treatment, emphasizing the need for further research.