Table 2.

The relationship between Merkel cell carcinoma (MCC) specific survival and clinical characteristics (215 patients, 145 MCC‐specific deaths). Survival analysis was completed using a competing‐risks regression (non‐MCC causes of death were considered competing events). Stage at diagnosis (P = .53 univariate; P = .56 multivariate) and age at first metastasis (P = .51; P = .31) were not significantly associated with MCC‐specific survival (data not shown)

	Univariate			Multivariatea
				Grouped by most frequent initial metastatic sites			Grouped by M1 AJCC 8th edition substaging
	HR	95% CI	Global P‐value	HR	95% CI	Global P‐value	HR	95% CI	Global P‐value
Site of initial metastasis			.006			.009
Skin/ body wall (ref)	—	—		—	—
Lymph node	1.67	0.87‐3.20		1.97	1.01‐3.84
Liver	2.79	1.31‐5.96		2.13	1.00‐4.55
All other visceral sites	1.24	0.64‐2.42		1.26	0.64‐2.49
Multiple sites	2.35	1.24‐4.45		2.73	1.41‐5.31
Met site by AJCC substaging			.075						.170
M1a: skin/ lymph node (ref)	—	—					—	—
M1b: lung	0.89	0.42‐1.86					0.77	0.37‐1.60
M1c: all other sites	1.44	1.02‐2.04					1.29	0.90‐1.87
Immune suppression			<.001			<.001			<.001
Absent (ref)	—	—		—	—		—	—
Present	1.97	1.35‐2.88		2.15	1.41‐3.27		2.10	1.42‐3.11
Primary lesion site			.023			.215			.237
No identified primary (ref)	—	—		—	—		—	—
Head and neck	1.53	0.98‐2.37		1.09	0.62‐1.93		1.38	0.80‐2.39
Trunk	2.12	1.26‐3.58		1.18	0.54‐2.57		1.43	0.72‐2.85
Buttock & genitalia	0.97	0.46‐2.05		0.59	0.26‐1.36		0.75	0.34‐1.66
Upper limb	1.43	0.86‐2.39		1.11	0.61‐2.02		1.29	0.73‐2.26
Lower limb	0.90	0.55‐1.48		0.63	0.35‐1.15		0.80	0.44‐1.43
Patient sex			.080			.031			.046
Male (ref)	—	—		—	—		—	—
Female	0.67	0.42‐1.05		0.55	0.32‐0.95		0.59	0.35‐0.99

^aThe multivariate analyses included the following variables: site(s) of first distant metastasis, primary lesion site, sex, immune suppression status, age at first metastasis, and stage at diagnosis.