Table 2.
Evaluation of an association between SPLC and overall survival stratified by subgroups for assessing effect modification (ie, interaction)
| Data source and subgroup | Case | aHR of SPLCa (95% CI) | P interaction b |
|---|---|---|---|
| SEER | |||
| Stage at IPLCc | |||
| Early | 133 445 | 2.14 (2.08 to 2.20) | <.001 |
| Advanced | 5524 | 1.43 (1.21 to 1.70) | |
| Age at IPLC diagnosis, y | |||
| 0-49 | 7 986 | 3.10 (2.67 to 3.60) | |
| 50-59 | 22 608 | 2.79 (2.60 to 2.99) | <.001 |
| 60-69 | 45 396 | 2.31 (2.22 to 2.41) | |
| 70-79 | 48 391 | 1.93 (1.85 to 2.01) | |
| ≥80 | 14 588 | 1.50 (1.37 to 1.64) | |
| Histology of IPLC | |||
| Small cell | 1970 | 1.43 (1.14 to 1.79) | |
| Large cell | 4911 | 1.87 (1.65 to 2.12) | |
| Adenocarcinoma | 75 738 | 2.06 (1.99 to 2.14) | <.001 |
| Squamous cell | 35 666 | 2.16 (2.07 to 2.27) | |
| Non-small cell carcinoma/NOS | 5721 | 2.04 (1.81 to 2.28) | |
| Others | 14 963 | 2.40 (2.17 to 2.65) | |
| MEC | |||
| Smoking statusd | |||
| Former/Never | 983 | 1.41 (0.98 to 2.03) | .04 |
| Current | 557 | 2.31 (1.48 to 3.61) |
Time-varying predictor for overall survival. aHR = adjusted hazard ratio; CI = confidence interval; IPLC = initial primary lung cancer; MEC = Multiethnic Cohort Study; NOS = not otherwise specified; SEER = Surveillance, Epidemiology, and End Results Program; SPLC = second primary lung cancer.
2-sided likelihood ratio test comparing models with and without interaction with SPLC.
Stage of IPLC was defined using SEER summary stage: “localized” and “regional” for early stage and “distant” for advanced stage.
Assessment of smoking status was collected at baseline and updated using 10-year follow-up, if prior to IPLC diagnosis.