Treatment strategy for cutaneous malignant melanoma

Clinicopathological correlation for the role of fluorodeoxyglucose positron emission tomography computed tomography in detection of choroidal malignant melanoma

BACKGROUND

The purpose of this study was to redefine the role of whole-body 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography fused with computed tomography (PET/CT) in the clinical diagnosis of choroidal malignant melanoma.

METHODS

The study design was a retrospective case series involving 7 consecutive patients with choroidal malignant melanoma who underwent enucleation to reach the final pathological diagnosis. FDG-PET/CT was performed together with magnetic resonance imaging and ophthalmological examinations before the surgery. The area, thickness, longest diameter, and circumference of the tumor mass were measured on pathological sections, and were correlated with maximum standardized uptake values (SUVmax) of the tumors on FDG-PET/CT.

RESULTS

Abnormally high uptake of FDG was noted in the affected eyes of 5 patients, but not in the eyes of 2 patients. The 5 patients with high uptake showed nodular tumors extruding into the vitreous cavity while the 2 patients with absence of uptake showed diffusely infiltrating tumors in the wide area of the choroid with or without a small mushroom-like protrusion. One patient with diffuse infiltration showed concurrent liver metastases with high uptake on PET/CT while another patient with a nodular tumor developed liver metastases a year later. The tumors with higher SUVmax had a tendency to have a wider area and greater thickness on pathological sections (ρ = 0.775, P = 0.0557, Spearman rank correlation test).

CONCLUSIONS

FDG-PET/CT showed correlation of the uptake with tumor sizes but was limited in detecting diffusely infiltrating tumors in the choroid without nodular formation.

Laminin-421 produced by lymphatic endothelial cells induces chemotaxis for human melanoma cells

Melanoma has a high tendency to metastasize to lymph nodes, which is one of the clinicopathological factors to indicate poor prognosis. Recent investigations have shown the importance of lymphangiogenesis in lymph node metastasis in a variety of human tumors including melanoma. However, molecular mechanism of lymphatic metastasis is still poorly defined. We examined influence of interactions between normal lymphatic endothelial cells (LECs) and melanoma cells on cell migration. Medium conditioned with LEC (LEC-CM) contained chemotactic and chemokinetic activities for human melanoma cell lines. The chemotactic activity was fractionated in more than 100 kDa, and inactivated by heat-treatment. The chemotactic activity of LEC-CM was abolished by immunodepletion with anti-laminin-1 antibody. And immunoprecipitation and Western blot analyses revealed that LEC-CM contained laminin-421. When melanoma C8161 cells were treated with function-blocking antibodies to integrin alpha3 or alpha6, their chemotactic responses to LEC-CM were markedly reduced. Furthermore, the knock-down of tetraspanin CD151 weakened the chemotactic responses of C8161 and MeWo cells to LEC-CM. These data suggest that laminin-421 secreted by LEC possibly facilitates lymphatic metastasis through the induction of chemotaxis of melanoma cells.

Sentinel node biopsy versus elective lymph node dissection in patients with cutaneous melanoma in a Japanese population

BACKGROUND

In Japan, elective lymph node dissection (ELND) has been the standard treatment for patients with possible nodal melanoma. Sentinel node biopsy (SNB) has now replaced ELND, not only in Japan but also worldwide. The objective of this study was to compare the interim outcomes of SNB and ELND.

METHODS

A retrospective study was conducted among patients with clinically node-negative disease treated at our institute with either SNB (n = 30) or ELND (n = 72).

RESULTS

The background was similar in the two groups. Nodal metastases were found in 40.0% of patients in the SNB group, but in only 26.4% in the ELND group (P = 0.173). The median follow-up was 31.5 months for the SNB group and 82 months for the ELND group. The incidence of locoregional recurrence and distant metastasis in the SNB group was 10.0% and 16.7%, respectively, and for the ELND group the incidence was 5.6% and 31.9%, respectively. The 3-year disease-free survival rate was similar in the two groups (P = 0.280), and the 3-year disease-free survival rates for node-positive patients were also similar in the two groups (P = 0.90), as were the 3-year disease-free survival rates for node-negative patients (P = 0.193).

CONCLUSION

This interim result in a Japanese melanoma population with clinically node-negative disease demonstrated that SNB identified more nodal micrometastases than ELND. This increase in accurate staging likely resulted from the reliable identification of the lymph node field by lymphoscintigraphy, as well as the more detailed pathologic examination of the nodes removed in SNB. It is quite reasonable to perform SNB instead of ELND in this population.

Expression of a suicidal gene under control of the human secreted protein acidic and rich in cysteine (SPARC) promoter in tumor or stromal cells led to the inhibition of tumor cell growth

The successful use of transcriptional targeting for cancer therapy depends on the activity of a given promoter inside the malignant cell. Because solid human tumors evolve as a "cross-talk" between the different cell types within the tumor, we hypothesized that targeting the entire tumor mass might have better therapeutic effect. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein overexpressed in different human cancers malignant melanomas both in the malignant cells compartment as in the stromal one (fibroblasts and endothelial cells). We have shown that expression of the herpes simplex virus-thymidine kinase (TK) gene driven by the SPARC promoter in combination with ganciclovir inhibited human melanoma cell growth in monolayer as well as in multicellular spheroids. This inhibitory effect was observed both in homotypic spheroids composed of melanoma cells alone as well as in spheroids made of melanoma cells and stromal cells. Expression of the TK gene was also efficient to inhibit the in vivo tumor growth of established melanomas when TK was expressed either by the malignant cells themselves or by coadministered endothelial cells. Our data suggest that the use of therapeutic genes driven by SPARC promoter could be a valuable strategy for cancer therapy aiming to target all the cellular components of the tumor mass.