Table 3. Multivariate regression analysis of risk factors for the occurrence of metachronous CTGCTs during follow-up (death as competing risk).

	Non-seminoma TGCT only						All TGCTs
	Model 1			Model 2
Risk factor	HR	95% CI	P -value	HR	95% CI	P -value	HR	95% CI	P -value
Agea	0.75	0.55–1.00	0.049	0.74	0.55–1.00	0.053	0.67	0.54–0.83	<0.001
Histology						—			0.683
Seminoma	—	—	—	—	—		1.00	Ref
Non-seminoma	—	—	—	—	—		0.89	0.52–1.52
Chemotherapy b			0.001			—			—
No	1.00	Ref		—	—		—	—
Yes	0.31	0.16–0.60		—	—		—	—
Chemotherapy b			—			0.003			<0.001
None	—	—		1.00	Ref		1.00	Ref
Platinum-based CT	—	—		0.37	0.18–0.72		0.34	0.18–0.63
Other CT	—	—		0.11	0.01–0.78		0.17	0.04–0.72

Abbreviations: 95% CI=95% confidence interval; CTGCT=contralateral testicular germ cell tumour; CT=chemotherapy; HR=(subdistribution) hazard ratio; TGCT=testicular germ cell tumour.

Model 1: chemotherapy (CT) entered in the model as yes vs no.

Model 2: chemotherapy (CT) entered in the model as platinum-based CT or other CT (vs none).

^aAge, centred to the mean, continuous, every 10-year increase.

^bIncludes treatment for relapse/recurrence before metachronous CTGCT diagnosis.