[Colorectal cancer metastasis. Frequency, prognosis, and consequences].
BACKGROUND
In about 50% of colorectal cancer cases, metastases are responsible for tumour-specific death. This study examines influences on survival after diagnosis of metastases and conclusions that can be drawn from the time pattern of a progressive disease course.


METHODS
The background was provided by Munich Cancer Registry database (Germany). Population-based, good follow-up, high quality of clinical data, and results comparable to those of other cancer registries stand for validity of these data.


RESULTS
Number of positive lymph nodes is the best prognostic factor. However, since metastasis may be initiated before diagnosis of the primary tumour, growth of the primary tumour and the metastases may be two autonomous processes. Thus survival following metastasis is almost unrelated to prognostic factors from the primary tumour, and median survival time after diagnosis of metastases is therefore almost comparable with 17 months. From the distribution of survival time after diagnosis of the primary tumour, the time from initiation of metastases to their diagnosis can be estimated at about 6 years. This means that metastases diagnosed synchronously with the primary tumour (M1) were initiated 6 years before detection of the primary tumour and also that metastases diagnosed during follow-up had already started before therapy of the primary tumour. In consequence, positive lymph nodes are an indicator but not a cause of metastases.


CONCLUSIONS
Specific time relations support the hypothesis that all metastases were initiated before diagnosis of the primary tumour. This hypothetic model has a high explanatory potential, also for evidence of the missing survival benefit from radical lymph node dissection.
Hölzel
D
D
Institut für Med. Informationsverarbeitung, Biometrie und Epidemiologie (IBE), Ludwig-Maximilians-Universität, Klinikum Grosshadern, Marchioninistrasse 15, Munich, Germany. hoe@ibe.med.uni-muenchen.de
Eckel
R
R
Engel
J
J
D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D005858:Germany; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D012042:Registries