Cancer Res Treat.  2018 Jan;50(1):183-194. 10.4143/crt.2016.532.

The Clinical Significance of Occult Gastrointestinal Primary Tumours in Metastatic Cancer: A Population Retrospective Cohort Study

• Hannouf MB
• Winquist E
• Mahmud SM
• Brackstone M
• Sarma S
• Rodrigues
• Rogan PK
• Hoch JS
• Zaric GS

• KMID: 2403488
• DOI: http://doi.org/10.4143/crt.2016.532

Abstract

PURPOSE
The purpose of this study was to estimate the incidence of occult gastrointestinal (GI) primary tumours in patients with metastatic cancer of uncertain primary origin and evaluate their influence on treatments and overall survival (OS).
MATERIALS AND METHODS
We used population heath data from Manitoba, Canada to identify all patients initially diagnosed with metastatic cancer between 2002 and 2011. We defined patients to have "occult" primary tumour if the primary was found at least 6 months after initial diagnosis. Otherwise, we considered primary tumours as "obvious." We used propensity-score methods to match each patient with occult GI tumour to four patients with obvious GI tumour on all known clinicopathologic features. We compared treatments and 2-year survival data between the two patient groups and assessed treatment effect on OS using Cox regression adjustment.
RESULTS
Eighty-three patients had occult GI primary tumours, accounting for 17.6% of men and 14% of women with metastatic cancer of uncertain primary. A 1:4 matching created a matched group of 332 patients with obvious GI primary tumour. Occult cases compared to the matched group were less likely to receive surgical interventions and targeted biological therapy, and more likely to receive cytotoxic empiric chemotherapeutic agents. Having an occult GI tumour was associated with reduced OS and appeared to be a nonsignificant independent predictor of OS when adjusting for treatment differences.
CONCLUSION
GI tumours are the most common occult primary tumours in men and the second most common in women. Patients with occult GI primary tumours are potentially being undertreated with available GI site-specific and targeted therapies.

Keyword

Neoplasm metastasis; Unknown primary neoplasms; Gastrointestinal neoplasms; Information storage and retrieval; Propensity score; Research design; Cohort studies

MeSH Terms

Biological Therapy
Canada
Cohort Studies*
Diagnosis
Female
Gastrointestinal Neoplasms
Humans
Incidence
Information Storage and Retrieval
Male
Manitoba
Neoplasm Metastasis
Neoplasms, Unknown Primary
Propensity Score
Research Design
Retrospective Studies*

Figure

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  Fig. 1. Overall survival analyses comparing patients with occult gastrointestinal (GI) primary tumours to patients with obvious GI primary tumours.

Reference

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