Different pathologic types of early stage lung adenocarcinoma have different post-operative recurrence patterns

Objectives: To accurately describe the pattern, timing and predictors of disease recurrence after curative resection for different types of early-stage lung adenocarcinoma (LUAD).

Methods: A total of 1962 patients with early-stage LUAD were included. The presence of micropapillary, solid components or poorly differentiated cancer as a clinical variable was named "high-grade" adenocarcinoma (HGADC), while others were classified as "low-grade" adenocarcinoma (LGADC). Predictive factors for specific recurrence patterns were assessed by univariate and multivariate analyses using Cox-proportional hazard regression models. Event dynamics, based on the hazard rate, were evaluated.

Results: At a median follow-up of 36.0 months, 137 (6.98%) of 1962 patients suffered from recurrence. Multivariable Cox analysis revealed that HGADC was an independent predictor for overall recurrence (hazard ratio [HR] 3.08, 95% confidence interval [CI] 2.09-4.52, p < 0.001), local recurrence (HR 2.77, 95% CI 1.38-5.55, p < 0.001), distant metastasis (HR 3.22, 95% CI 2.03-5.11, p < 0.001), chest recurrence (HR 2.80, 95% CI 1.65-4.75, p < 0.001) and brain recurrence (HR 4.11, 95% CI 1.83-9.22, p < 0.001). However, HGADC (HR 1.56, 95% CI 0.63-3.86, p = 0.335 in univariate analysis) was not a risk factor for bone recurrence. The hazard curve of the whole group presented a double-peaked pattern. Different types of LUAD had different hazard curves. HGADC patients exhibited higher hazard rates than LGADC patients during the whole follow-up. In addition, the recurrence hazard curve in HGADC patients showed a typical "double-peaked" pattern, while the curve in LGADC patients displayed a smooth curve after surgery.

Conclusions: Different postoperative recurrence patterns were seen in HGADC and LGADC. Site-specific recurrence patterns were also different in HGADC and LGADC types.