Table 1 Criteria to assess the relevance of studies included in the analysis

Internal validity

Generalities

 Is the hypothesis/aim/objective of the study clearly described?

3

 Are the main findings/results/outcomes clearly described?

3

 Are the characteristics of the patients included described?

(3)

  Socio-demographic

1

  Disease/treatment-related

1

  Work-related

1

Study design and methods

 Data collection

  Population-based

3

  Regionally based (or several settings)

2

  Hospital/centre-based

1

 Were the groups equivalent at baseline (or adjusted)?

(3)

  Socio-demographic characteristics

1.5

  Work-related characteristics

1.5

 Number subjects included

  ≥500

3

  ≥50, <500

2

  <50

1

 Length of follow-up (since diagnosis or treatment)

  ≥1 year

3

  ≥6 months

2

  ≥3 months

1

 Loss of follow-up = less than 5 %

2

External validity

Number of cancer sites

 >10

3

 4–10

2

 ≥3

1

Were the subjects representative of the population from which they were recruited?

3

Total (maximum)

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