To determine the diagnostic accuracy of sentinel lymph node biopsy (SLNB) for the detection of nodal metastases (in the investigated nodal basin) for the staging of cutaneous squamous cell cancer (cSCC).

To determine the diagnostic accuracy of imaging tests, including ultrasound, computed tomography, magnetic resonance imaging and positron emission tomography, alone or in combination, for the detection of any metastasis for the staging of cutaneous squamous cell cancer.

To determine the diagnostic accuracy of imaging tests for the detection of nodal metastases in the staging of cutaneous squamous cell cancer.
To determine the diagnostic accuracy of imaging tests for the detection of distant metastases in the staging of cutaneous squamous cell cancer.

We will estimate these separately for those undergoing primary staging and those who have experienced a disease recurrence.

Sources of heterogeneity

We will consider a range of potential sources of heterogeneity for investigation in each individual test review. These may vary between reviews but may include the following.

i. Population characteristics

• Primary tumour site (head and neck, trunk, limb, and other)
• Primary staging versus mixed or unclear populations (i.e. including staging of recurrent disease)

ii. Index test characteristics

• Differences in test positivity thresholds

iii. Reference standard characteristics

• Reference standard used (histology, clinical or imaging-based follow-up)

iv. Study quality

• Consecutive or random sample of participants recruited
• Index test interpreted blinded to the result of any other index test
• Presence of partial or differential verification bias (whereby only a sample of those subject to the index test are verified by the reference test or by the same reference test with selection dependent on the index test result)
• Use of an adequate reference standard
• Overall risk of bias

We anticipate that the volume of evidence retrieved will be small and will restrict our ability to formally investigate these sources of heterogeneity; however, data permitting, we will examine any impact on the effectiveness of each index test for the primary target condition and make recommendations for where further research might be required.