Background The number of persons with thyroid nodules has increased rapidly in recent years, and thyroid cancer caused by malignant nodules has become a key problem endangering the health of young and middle-aged groups in China.

Objective To explore work and lifestyle influencing factors for developing thyroid cancer among young and middle-aged patients with thyroid nodules.

Methods The subjects with thyroid nodules were reported by routine physical examines ordered at the Huadong Sanatorium. We conducted a 1∶4 matched case-control study in which 232 patients diagnosed with thyroid cancer from 2012 to 2022 were matched to 928 controls by gender and age (±5 years). A validated questionnaire was used to collect data on work and lifestyle behaviors. Univariate and multivariate logistic regression models were applied to explore potential relationships between selected factors (including environment, working hours, stress, diet, exercise, and mental health) and thyroid cancer. Spearman rank correlation was used to analyze the correlations between variables.

Results The results of univariate logistic regression showed a history of thyroid cancer reported among first-degree relatives (OR=6.059, 95%CI: 1.007, 36.473), obesity (OR=1.973, 95%CI: 1.296, 3.004), noise and vibration exposure (OR=1.988, 95%CI: 1.143, 3.456), frequent stress (OR=2.093, 95%CI: 1.231, 3.559), frequent depression (OR=2.034, 95%CI: 1.048, 3.947), frequent anger (OR=1.791, 95%CI: 1.066, 3.012), frequent fried food diet (OR=1.535, 95%CI: 1.026, 2.297), and frequent fast food diet (OR=1.836, 95%CI: 1.048, 3.215) were risk factors for reporting thyroid cancer developing from thyroid nodules, while regular meals (OR=0.245, 95%CI: 0.061, 0.989) and frequent exercise (OR=0.571, 95%CI: 0.342, 0.952) were protective factors for reporting no thyroid cancer. The results of Spearman correlation analysis showed that body mass index was positively correlated with frequent fried food, fast food, and sugary beverage diets (r=0.123, 0.083, 0.077, P<0.01), and negatively correlated with frequent depression and anger (r=−0.090, −0.070, P<0.05). The results of multiple logistic regression found that a history of thyroid cancer reported among first-degree relatives (OR=6.712, 95%CI: 1.071, 42.066), obesity (OR=2.032, 95%CI: 1.321, 3.125), noise and vibration exposure (OR=1.991, 95%CI: 1.089, 3.637), and frequent stress (OR=2.468, 95%CI: 1.417, 4.300) were associated with an elevated risk of reporting thyroid cancer developing from thyroid nodules patients. Regular exercise (frequency≥3 times·week⁻¹, > 30 min per episode) (OR=0.516, 95%CI: 0.300, 0.890) was associated with a lowered risk of reporting thyroid cancer.

Conclusions Multiple risk factors associated with reporting thyroid cancer among young and middle-aged groups with thyroid nodules are identified, such as obesity, noise and vibration exposure, frequent stress, and lack of exercise.