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.