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Fleischner Society-Guided Follow-up of Incidentally Detected Pulmonary Lesions During the COVID-19 Pandemic Enables Early Lung Cancer Detection While Avoiding Unnecessary Pulmonary Resection

This retrospective study demonstrates that managing incidentally detected pulmonary lesions found during COVID-19 screening according to Fleischner Society guidelines successfully facilitated early detection of curable lung cancer while significantly reducing unnecessary pulmonary resections and achieving excellent long-term survival outcomes.

Original authors: Leyla Nesrin Acar, Pınar Bıçakçıoğlu, Seray Hazer, Nesrin Gürçay, Selim Şakir Erkmen Gülhan

Published 2026-07-07

📖 4 min read☕ Coffee break read

CC BY 4.0

Original authors: Leyla Nesrin Acar, Pınar Bıçakçıoğlu, Seray Hazer, Nesrin Gürçay, Selim Şakir Erkmen Gülhan

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine your lungs are like a vast, quiet forest. Usually, this forest is clear, but sometimes, a storm passes through (in this case, the COVID-19 pandemic). When the storm hits, it leaves behind a lot of debris: fallen branches, muddy puddles, and strange-looking mounds of dirt.

In the medical world, doctors use special "storm scanners" (CT scans) to check the forest. Because everyone was getting scanned to check for the storm itself, doctors suddenly found thousands of these "mounds of dirt" (pulmonary nodules) that they wouldn't have noticed otherwise.

The big question was: Are these mounds dangerous monsters (cancer) that need to be dug up immediately, or are they just harmless mud that will dry up and disappear on its own?

Here is how this study solved that mystery, using a simple "rulebook" called the Fleischner Society Guidelines.

The "Wait and Watch" Strategy

Instead of rushing to dig up every single mound (which would mean unnecessary surgery), the doctors followed a specific set of instructions. Think of this like a gardener's rulebook:

If a sprout looks suspicious, don't pull it out immediately.
Wait and watch it for a few months.
If it grows bigger or changes shape, then you dig it up.
If it shrinks or disappears, it was just a weed or a temporary patch of dirt, and you saved yourself a lot of work.

What Happened in the Study?

The researchers looked at 179 patients who had these "mounds" found by accident during the pandemic. They put them on this "Wait and Watch" plan.

1. The "False Alarms" Disappeared
About 24% of the time (43 patients), the "mounds" simply vanished on their own.

The Metaphor: It was like a puddle of rain drying up in the sun. These were actually just inflammation or scarring from the virus, not cancer.
The Result: Because they waited, these 43 people avoided surgery entirely. They didn't need to have a piece of their lung cut out for something that wasn't dangerous.

2. The "Real Monsters" Were Caught Early
For the patients whose "mounds" didn't go away, the doctors operated.

The Metaphor: The rulebook helped them find the real monsters before they grew too big to catch.
The Result: Most of the cancers found were in the very early stages (Stage I or II). Because they were caught early, the "forest" could be cleared successfully.
- Survival: 87% of patients were still alive 5 years later.
- No Recurrence: 92% of patients had no sign of the cancer coming back after 5 years.

The "Bad News" vs. "Good News" Mix

The study found something unique about the "mounds" found during the pandemic.

Before the pandemic: Most harmless mounds were usually just harmless growths like hamartomas (like a small, harmless rock in the forest).
During the pandemic: The most common harmless mounds were scars and inflammation from the virus itself (like mud and debris).
Why this matters: If doctors had operated immediately on these pandemic-era mounds, they would have cut out a lot of healthy lung tissue that was just healing. The "Wait and Watch" rule prevented this mistake.

The "Red Flags"

The study also figured out which "mounds" were most likely to be real monsters. If a patient had these three traits, the odds of it being cancer went up:

Older age (70+).
Being male.
Heavy smoking history (smoking a lot for many years).

The Bottom Line

This study proves that when doctors find a suspicious spot in the lung, patience is a superpower.

By following the "Fleischner Rulebook" and waiting to see if the spot disappears or grows, doctors can:

Save people from unnecessary surgery (avoiding cutting out healthy lungs).
Catch the real cancer early (when it's easiest to cure).
Get excellent long-term results for the patients who do need surgery.

In short: Don't panic and dig up the whole forest just because you see a strange spot. Wait, watch, and let the rulebook guide you. It saves the forest from unnecessary damage and catches the real threats before they get too big.

Technical Summary: Fleischner Society-Guided Follow-up of Incidentally Detected Pulmonary Lesions During the COVID-19 Pandemic

Problem Statement
The widespread utilization of thoracic computed tomography (CT) for evaluating suspected SARS-CoV-2 pneumonia during the COVID-19 pandemic led to an unprecedented increase in the incidental detection of pulmonary nodules, ground-glass opacities (GGOs), and masses. A significant clinical challenge arose in distinguishing transient inflammatory abnormalities—such as organizing pneumonia, ischemic necrosis, and post-inflammatory fibrosis, which are common sequelae of COVID-19—from early-stage lung cancer. Immediate surgical intervention for these lesions risked unnecessary pulmonary resections, while delayed diagnosis could compromise the curability of malignancies. Although the Fleischner Society published updated recommendations in 2017 for managing incidental nodules, there was limited evidence regarding the long-term oncological outcomes of applying these guidelines specifically to the unique cohort of patients with incidental findings during the pandemic, particularly regarding the balance between avoiding unnecessary surgery and ensuring early cancer detection.

Methodology
This study was a retrospective, single-center observational analysis conducted at Ankara Atatürk Sanatorium Education and Research Hospital. The cohort consisted of patients who underwent thoracic CT between April 1, 2019, and April 1, 2021, due to suspected COVID-19 infection.

Patient Selection: From an initial pool of 259 patients with incidental findings, 197 patients with definitive postoperative histopathological diagnoses formed the final study cohort. Patients with a history of malignancy or incomplete records were excluded.
Surveillance Protocol: Patients presenting with pulmonary masses ( $n=61$ ) underwent immediate multidisciplinary evaluation and resection. Patients with pulmonary nodules or GGOs ( $n=179$ ) were enrolled in a structured surveillance program adhering strictly to the 2017 Fleischner Society recommendations.
Intervention Criteria: Lesions demonstrating complete regression or substantial radiological improvement during surveillance were managed conservatively. Persistent, enlarging, or suspicious lesions underwent pulmonary resection (wedge resection, segmentectomy, lobectomy, etc.) with lymph node dissection as indicated.
Data Analysis: The study analyzed demographic variables, clinical risk factors (including smoking history), radiological features, and histopathological outcomes. Multivariable logistic regression was used to identify independent predictors of malignancy. Survival outcomes (Overall Survival [OS] and Disease-Free Survival [DFS]) were estimated using the Kaplan–Meier method.

Key Results

Avoidance of Unnecessary Surgery: Among the 179 patients entering the surveillance program, 43 (24.0%) demonstrated spontaneous radiological regression and avoided pulmonary resection. Follow-up of 38 of these patients (median 8 months) confirmed complete resolution without subsequent need for surgery.
Pathological Spectrum: In the benign group, ischemic necrosis and organizing pneumonia predominated, collectively accounting for over 80% of diagnoses. This contrasts with pre-pandemic series where hamartomas are more common, reflecting the specific inflammatory and vascular sequelae of SARS-CoV-2.
Predictors of Malignancy: Multivariable analysis identified three independent predictors of malignant histopathology:
- Age $\ge$ 70 years (Adjusted OR 5.50)
- Male sex (Adjusted OR 2.28)
- Heavy smoking history ( $\ge$ 20 pack-years; Adjusted OR 3.49)
Oncological Outcomes: Of the 148 patients with malignant lesions, the majority were diagnosed at early stages: 51.4% Stage I and 29.7% Stage II. No Stage IV disease was found in the surgically treated group.
- 5-Year Overall Survival (OS): 87.2%
- 5-Year Disease-Free Survival (DFS): 92.6%
- Patients with Stage I–II disease demonstrated significantly better survival rates compared to Stage III disease ( $p=0.0000$ ).

Significance and Claims
The paper claims that the strict implementation of the Fleischner Society recommendations during the COVID-19 pandemic successfully optimized patient selection for surgery. The study demonstrates that guideline-based surveillance:

Prevented Unnecessary Resections: Safely identified and managed transient inflammatory lesions that would have otherwise undergone unnecessary invasive procedures.
Facilitated Early Detection: Enabled the diagnosis of lung cancer predominantly at surgically curable stages (Stage I–II), leading to excellent long-term oncological outcomes.
Validated Risk Stratification: Confirmed that integrating structured radiological surveillance with clinical risk factors (age, sex, smoking) is essential for distinguishing inflammatory mimics from malignancy.

The authors conclude that multidisciplinary evaluation, combined with individualized risk assessment and guideline-based surveillance, should remain the cornerstone of management for incidentally detected pulmonary lesions, particularly in contexts where inflammatory pulmonary abnormalities are prevalent. The study supports the routine adoption of Fleischner Society recommendations to balance the risks of delayed diagnosis against the harms of unnecessary surgery.