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Risk factors differ for lymphatic, hematogenous metastasis

As the risk factors associated with lymphatic and hematogenous metastasis differ, follow-up and treatment strategies may need to be adapted, according to researchers.

“These observations indicate that the presence of tumor regression could perhaps help to distinguish between lymphatic and hematogenous metastasis and suggest that regression could be associated with good outcomes,” Laura Calomarde-Rees, MD, of the department of dermatology at Instituto Valenciano de Oncología in Valencia, Spain, and colleagues wrote.

The retrospective cohort study included 1,177 patients (median age at diagnosis, 55 years; 51.1% women) with stage I to II melanoma diagnosed and treated at the Instituto Valenciano de Oncología from January 2000 and diagnosed through December 2015.

The primary variable studied was the site of the first metastasis, and researchers distinguished between lymphatic dissemination and hematogenous metastasis.

In all, 1,026 patients did not develop metastasis, 108 patients developed lymphatic metastasis and 108 developed hematogenous metastasis, the researchers reported.

Statistically significant variables in the univariate analysis of risk factors for lymphatic metastasis were being older than 55 years (HR = 2.2; 95% CI, 1.5-3.3), location in the head/neck (HR = 3; 95% CI, 1.9-4.6) and acral sites (HR = 3.8; 95% CI, 2.2-6.5), ulceration (HR = 2.8; 95% CI, 1.8-4.3), a higher miotic rate (HR = 4.5; 95% CI, 2.2-9.3), vascular invasion (HR = 5.7; 95% CI, 2.3-13.9) and the presence of BRAF mutations (HR = 1.9; 95% CI, 1.2-3.2).

In hematogenous metastasis, being older than 55 years (HR = 1.8; 95% CI, 1.3-2.7) was a risk factor.

Other risk factors were location in the head/neck (HR = 3.1; 95% CI, 2-4.7), greater Breslow thickness (HR = 4.2; 95% CI, 2.3-7.8), ulceration (HR = 4.4; 95% CI, 2.9-6.6) and high mitotic rate (HR = 13.2; 95% CI, 5.9-29.3). Researcher also found that presence of BRAF (HR = 2.5; 95% CI, 1.6-4.1) and TERT (HR = 2.8; 95% CI, 1.6-4.7) mutations were defined risk factors. Furthermore, female sex had a protective effect (HR = 0.5; 95% CI, 0.3-0.7).

“Vascular invasion was significantly associated with lymphatic metastasis only, suggesting that tumor emboli are preferentially located in lymph vessels, a fact that was confirmed in our series because the lymphatic nature of invaded vessels was routinely assessed by immunohistochemistry,” the researchers wrote. – by Abigail Sutton

Disclosure s : The authors report no relevant financial disclosures.