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NCT Number: NCT07564089

Thymus Dosimetric and Morphologic Predictors of Radiation-Induced Lymphopenia in Stage III NSCLC

This study is being done to find out whether features of the thymus gland can predict a common side effect of radiation therapy for lung cancer called radiation-induced lymphopenia.

We will include adults with stage III non-small cell lung cancer (NSCLC) who are scheduled to receive curative radiation therapy to the chest, with or without chemotherapy.

Before, during, and after radiation therapy, we will measure:

The dose of radiation that reaches the thymus gland (based on each patient's treatment plan)

The size and shape of the thymus gland (using CT scans taken for radiation planning)

The number of lymphocytes (a type of immune cell) in routine blood samples

The main goal is to see if certain radiation doses to the thymus, or a smaller thymus size, can predict severe lymphopenia. We will also check whether lymphopenia affects patient outcomes such as infections or survival.

This is an observational study (no added treatment or drug) - patients will receive their standard radiation therapy as planned by their doctor. The study only collects and analyzes data from standard scans and blood tests.

Potential benefits: Findings may help doctors design "immune-sparing" radiation plans in the future to reduce lymphopenia. Potential risks: There are no additional risks beyond standard radiation therapy, as this study does not change your treatment.

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This study is active but is not currently recruiting participants.

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Key information

Conditions

Radiation-induced Lymphopenia Number of Lymphocytes Thymus Dosimetric

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Jiangxi Cancer Hospital

Nanchang, Jiangxi, 330000, China

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Age ≥ 18 years;
Pathologically or cytologically confirmed primary non-small cell lung cancer (NSCLC) with a clinical stage of III (according to the 8th edition or latest version of the AJCC staging system);
Eligible for radical radiotherapy or chemoradiotherapy to the chest, with a planned total dose of ≥50 Gy to the chest, using a fractionation schedule of 1.8-2.0 Gy per fraction (conventional fractionation) or a high-dose fractionation regimen permitted by the protocol;
Planned to undergo periodic blood tests before and after radiotherapy, including absolute lymphocyte count;
ECOG performance status of 0-2;
Able to undergo regular follow-up and provide blood samples and imaging evaluations as required by the protocol.

Exclusion criteria

Previous history of thoracic or whole-body radiation therapy;
A diagnosis of radiation-induced lymphocytopenia or baseline lymphocytopenia graded ≥ Grade 2 (according to the CTCAE criteria) prior to study enrollment;
Patients with a history of or known primary immunodeficiency, active autoimmune disease, long-term systemic glucocorticoid therapy (prednisone-equivalent dose > 10 mg/day), or long-term use of immunosuppressants following organ transplantation;
History of concurrent malignancy (excluding basal cell carcinoma of the skin or cervical carcinoma in situ that has been treated curatively and has been recurrence-free for at least 5 years);
Pregnant or lactating women;
Any other condition deemed by the investigator to render the subject unsuitable for participation in this clinical study, including severe hepatic, renal, hematologic, or other organ dysfunction;
Irreversible contraindications to the radiotherapy plan or dose delivery.

Treatment and study plan

Definitive Thoracic Radiotherapy

Radiation

Patients with stage III non-small cell lung cancer (NSCLC) receive standard-of-care definitive radiotherapy to the chest, with or without concurrent/sequential chemotherapy. Radiotherapy is delivered using conventional fractionation (typically 1.8-2.0 Gy per fraction, total dose 50-66 Gy) or hypofractionated regimens as per institutional protocols. Treatment planning is performed using intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT) For the purposes of this observational study, the radiation dose-volume parameters of the thymus gland (e.g., Dmean, V5Gy, V10Gy, V20Gy) are extracted from each patient's treatment planning system. Morphologic features of the thymus (volume, density, transverse diameter) are measured from planning CT scans.

Other names: IMRT / VMAT for NSCLC, Chest radiotherapy, Thoracic radiation therapy

Primary outcomes

Severe radiation-induced lymphopenia (grade ≥3)

Time frame: From baseline (within 7 days before radiotherapy initiation) to 6 weeks after completion of radiotherapy.

Occurrence and severity of radiation-induced lymphopenia during definitive thoracic radiotherapy for stage III non-small cell lung cancer. Lymphopenia is defined based on absolute lymphocyte count (ALC) measured from peripheral blood samples. Severity is graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 5.0:

Grade 1: ALC < lower limit of normal to 800 cells/μL

Grade 2: ALC 500 - <800 cells/μL

Grade 3: ALC 200 - <500 cells/μL

Grade 4: ALC <200 cells/μL

The primary analysis will focus on grade ≥3 lymphopenia as the main endpoint. Absolute lymphocyte count nadir (lowest value during treatment) and relative change from baseline are also captured as continuous secondary measures within this outcome.
radiation-induced lymphopenia

Time frame: From baseline (within 7 days before radiotherapy initiation) to 6 weeks after completion of radiotherapy. ALC is measured at least weekly during radiotherapy, at the end of radiotherapy, and at 4-6 weeks post-radiotherapy.

Occurrence and severity of radiation-induced lymphopenia during definitive thoracic radiotherapy for stage III non-small cell lung cancer. Lymphopenia is defined based on absolute lymphocyte count (ALC) measured from peripheral blood samples. Severity is graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 5.0.

Grade 1: ALC < lower limit of normal to 800 cells/μL Grade 2: ALC 500 - <800 cells/μL Grade 3: ALC 200 - <500 cells/μL Grade 4: ALC <200 cells/μL The primary analysis will focus on grade ≥3 lymphopenia as the main endpoint. Absolute lymphocyte count nadir (lowest value during treatment) and relative change from baseline are also captured as continuous secondary measures within this outcome.

Sponsors and collaborators

Lead sponsor

You Peimeng

Other

Registry information

Important dates

Study start: 2026
Primary completion: 2027
Study completion: 2028
First posted: May 4, 2026
Registry last updated: May 4, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.