Merkel Cell

PEARLS

  • 10% present with distant metastases (skeletal or visceral) at presentation

PRIMARY TREATMENT

SURGERY of PRIMARY

  • Is the initial treatment in patients with operable disease w/o distant metastases.
  • Therapeutic resection of pathologically involved regional nodes.
  • some small tumor may be treated with WLE alone (controversial)
  • MARGIN: 2-3 cm margin is recommended.

RADIATION of PRIMARY

  • inoperable
  • metastatic disease
  • recurrence requiring multiple surgical excision

NODAL TREATMENT (clinically node negative)

  • Most all (except small tumors) will need elective nodal treatment
    • Surgical evaluation
    • prophylatic radiation
  • Alternative: sentinel node biopsy
    • SLND+: elective nodal treatment
    • SLND-: no further treatment
  • 30-50% rate of nodal relapse in patients with lesions < 1.0 cm.

NODAL TREATMENT (clinically node positive)

  • need both surgery and adjuvant locoregional radiotherapy
  • surgery alone has 26% nodal recurrenct.

POST-OPERATIVE RT

Indications

  • close or positive margins (gross residual)
  • multiple involved nodes
  • extranodal tumor extension
  • or some advocate for all cases of Merkel Cell

FIELD SETUP AND DOSE

  • 46-50 Gy to Elective irradiation in 2 Gy fractions
  • 66-70 Gy to Gross disease
  • primary target is 4-5 cm around the surgical bed
  • draining LN such as ipsilateral neck (for H&N primary)

CHEMOTHERAPY

  • recommended for distant control (no clear survival advantage)

RECURRENT DISEASE

  • median survival 6-12 months.
  • 20 to 30% with local only recurrence potentially curable.

METASTASIS

  • Patient with distant disease often still warrant local treatment, usually palliative radiotherapy, although in selected cases palliative surgery may be considered.
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