Abstract Body (Do not enter title and authors here): Background:
Pulmonary hypertension (PH) and lung cancer (LC) are both significant public health issues with substantial morbidity and mortality. Recent studies suggest potential associations between pulmonary vascular diseases and LC due to shared risk factors and pathophysiological mechanisms, yet comprehensive research in large populations is scarce.

Methods:
This prospective cohort study utilized data from the UK Biobank, with baseline assessment between 2006 and 2010 and follow-up until November 30, 2023, for England and Scotland, and May 31, 2022, for Wales. We included 6,425 participants with LC, identified using linked cancer registry data, and followed them for the incidence of PH over a period of 10 years. We adjusted for potential confounders including age, ethnics, sex, smoking status, BMI, and histologic subtypes of LC. Statistical analyses were performed using Time-dependent Cox proportional hazards models to estimate the associations between PH and LC.

Results:
Of 502,173 participants in this prospective cohort, 6,425 were diagnosed with LC, while 494,451 did not receive the LC diagnosis. The prevalence of PH in the LC cohort and the no-LC cohort were 0.64% (1,494 of 3,142 women [47.55%]) and 2.40% (59 of 154 women [38.31%]), respectively, with significant difference between the two groups (p<0.001). In the LC cohort, the mortality rates of patients without PH and with PH were 69.18% and 77.92% (p=0.020). Among the patients diagnosed with LC and PH, 33.12% were diagnosed with LC after PH (PH-LC), while 66.88% were diagnosed with LC before PH (LC-PH). And the mortality rates of the PH-LC group and the LC-PH group were 78.43% and 77.67%, respectively, with no significant difference between the two groups (p=0.915). Time-dependent Cox regression analysis showed that PH shows an increasing trend in risk (5th year HR: 3.22, 95% CI: 2.09-4.99, p-value < 0.001), highlighting its significant impact on LC long-term prognosis.

Conclusion:
To conclude, the presence of PH significantly increased the risk of mortality in participants with LC, especially for the long-term LC survivors. And certain percentage of patients were diagnosed with LC before PH, but they had no significant difference between the patients with LC after PH.