Identification and survival outcomes of a cohort of patients with cancer of unknown primary in Ontario, Canada

Abstract

background. Cancer of unknown primary origin (CUP) is defined by the presence of pathologically identified metastatic disease without clinical or radiological evidence of a primary tumour. Our objective was to identify incident cases of CUP in Ontario, Canada, and determine the influence of histology and sites of metastases on overall survival (OS). Material and methods. We used the Ontario Cancer Registry (OCR) and the Same-Day Surgery and Discharge Abstract Database (SDS/DAD) to identify patients diagnosed with CUP in Ontario between 1 January 2000, and 31 December 2005. Patient diagnostic information, including histology and survival data, was obtained from the OCR. We cross-validated CUP diagnosis and obtained additional information about metastasis through data linkage with the SDS/DAD database. OS was assessed using Cox regression models adjusting for histology and sites of metastases. results. We identified 3564 patients diagnosed with CUP. Patients without histologically confirmed disease (n  1821) had a one-year OS of 10.9%, whereas patients with confirmed histology (n  1743) had a one-year OS of 15.6%. The most common metastatic sites were in the respiratory or digestive systems (n  1603), and the most common histology was adenocarcinoma (n  939). Three-year survival rates were 3.5%, 5.3%, 41.6% and 3.6% among adenocarcinoma, unspecified carcinoma, squamous cell carcinoma and undifferentiated histology, respectively. Three-year survival rates were 40%, 2.4%, 8.0% and 4.6% among patients with metastases localised to lymph nodes, the respiratory or digestive systems, other specified sites, and unspecified sites, respectively. conclusion. CUP patients in Ontario have a poor prognosis. Some subgroups may have better survival rates, such as patients with metastases localised to lymph nodes and patients with squamous cell histology.

2018 consensus statement by the Spanish Society of Pathology and the Spanish Society of Medical Oncology on the diagnosis and treatment of cancer of unknown primary

“…Among histological factors, adenocarcinomas and undifferentiated tumours have a worse prognosis (3.5% 3-year survival) than squamous cell carcinomas (41.6% 3-year survival) [ 59 ].…”

The Diminishing Importance of Primary Site Identification in Cancer of Unknown Primary: A Canadian Single-Center Experience

“…Despite the steady decline in CUP incidence from 5% since the 1980s to around 2% of all new invasive cancer diagnoses, the prognosis for patients remains poor and is the fourth most common cause of cancer death (2)(3)(4). From 2000 to 2005, 3,564 new cases of CUP were diagnosed in Ontario, Canada (5).…”

A Simple Risk Model to Predict Survival in Patients With Carcinoma of Unknown Primary Origin

“…Previous studies have aimed to identify prognostic factors in patients with CUP. Gender, 21 performance status, 9 , 11 , 12 , 20 – 24 and number of organs involved and histological subtype 16 – 18 were the most frequently reported prognostic factors for patients with CUP in Western countries. This study identified that the independent predictors of survival time were visceral organ involvement, ECOG score and NLR in an Asian population.…”

“…Due to the heterogeneous clinical presentation and outcome of CUPs, appropriate patient selection and management might help to identify subsets of patients with more favorable outcomes. Several previous studies have reported clinical variables, including histological type, 16 – 18 metastatic site, 10 , 12 , 13 , 16 , 19 – 21 and functional performance of the patients, 9 , 11 , 12 , 20 – 24 having significant impact on survival in patients with CUPs. However, all of the previous studies were limited to Western populations; data regarding the prognostic factors in Asian populations with CUPs are very limited.…”