This case-sensitive code system http://fhir.ch/ig/ch-crl/CodeSystem/nkrs-methodfirstdetection defines the following codes:

Code	Display	Definition
1	Clinical symptoms	Clinical symptoms related to the tumour.
2	Incidental discovery	Diagnosis on the occasion of surveillance/treatment for another disease, incl. tumour aftercare for a previous primary tumour, routine medical consultation/routine check-up, surgery.
3	Organised screening program	Screening programmes organized at national or regional level, with an explicit policy, that includes several essential elements from target population to treatment. Screening refers to a targeted examination/search for an asymptomatic tumour.
4	Opportunistic screening	Screening outside an organized or population-based screening programme, as a result of, for example, a recommendation made during a routine medical consultation/check-up for the woman, on the basis of a possibly increased risk for developing cervical cancer or by self-referral. Screening refers to a targeted examination/search for an asymptomatic tumour.
5	Self-examination	Use this code if it is known that the chain of events leading to a diagnosis of cancer was a self-exam by the patient (e.g. a lump in the breasts, or a skin lesion).
6	Death with autopsy	Cancer diagnosed after death.
7	Death without autopsy	Cancer diagnosed after death.
8	Other