# Unilateral upper lung field pulmonary fibrosis after primary lung cancer surgery as a late complication to be recognized

## TL;DR

This study identifies unilateral upper lung field pulmonary fibrosis as a late complication after lung cancer surgery, affecting about 4% of patients and linked to several risk factors.

## Contribution

The study is the first to systematically analyze the incidence and risk factors for unilateral upper lung field pulmonary fibrosis after lung cancer surgery.

## Key findings

- Unilateral upper lung field pulmonary fibrosis occurred in 4.0% of patients after lung cancer surgery.
- Patients with unilateral UPF had a 76.9% chance of experiencing related complications like respiratory distress and pneumonia.
- Risk factors include age >75, male sex, low BMI, and specific lung conditions or tumor locations.

## Abstract

Unilateral upper lung field pulmonary fibrosis (UPF) is a possible complication on the operated side after lung cancer surgery. However, its incidence and associated perioperative factors remain unclear. This study investigated the clinical characteristics of patients with unilateral UPF after primary lung cancer surgery.

We reviewed the records of all consecutive patients with lung cancer who underwent complete resection at the Institute of Science, Tokyo, between July 2010 and December 2021. We estimated the cumulative incidence and sub-hazard ratios using competing risk regression models.

A total of 979 patients were included in this analysis. The median follow-up period up to the last follow-up was 59.2 months (interquartile range 37.0–84.6 months). With 39 (4.0%) cases of postoperative unilateral UPF, the median follow-up time until the diagnosis of unilateral UPF was 25.5 months (interquartile range 12.9–45.3 months), and the 3-, 5-, and 10-year cumulative incidences of unilateral UPF were 2.7%, 4.0%, and 5.4%, respectively. The 5-year overall survival rate was 87.3%; however, 30 of the 39 patients (76.9%) with unilateral UPF experienced subsequent complications related to unilateral UPF, such as progressive respiratory distress, progressive body weight loss, and pneumonia. Age > 75 years, male sex, low body mass index (< 20 kg/m2), ischemic heart disease, history of pneumonia, emphysema, pulmonary apical cap, and right lower lobe tumors are possible risk factors for unilateral UPF.

Unilateral UPF is an unrecognized late complication of lung cancer surgery that should be carefully monitored in patients with risk factors.