Cancer with Unknown Primary — Implementation of a Regional Referral Process and Clinical Practice Guidelines

Cancer patients without a known primary: incidence and survival trends in Sweden 1960-2007

BACKGROUND

Metastatic cancer from an unknown primary tumour (CUP) is a common and heterogeneous clinical entity. In Sweden like in many other countries, the continuum of care for such patients remains to be established.

MATERIAL AND METHODS

Data on CUP cases reported to the Swedish Cancer Registry during 1960 through 2007 was used to assess time trends for incidence, survival, and histological tumour type.

RESULTS

There was an upward trend for the age-adjusted incidence until the late 1990s. This roughly paralleled the increase for all reported cancers during the same period. The increase of CUP mainly concerned patients aged above 50 years, and tumours classified as adenocarcinomas. The relative survival at 12 months after a diagnosis of CUP was estimated at 20%. However, after 12 months the relative survival levelled of and the 5-year estimate was 10-15% which suggests that a small proportion of CUP cases may be cured. Relative survival was highly dependent on age with substantially better outcome for young patients, particularly those aged below 30 years. We observed no time trend for survival.

DISCUSSION

Cases diagnosed as CUP includes patients with metastatic spread from a wide variety of tumours although certain tumour types probably are overrepresented, for example, cancers in sites that are difficult to examine clinically. Incidence trends probably represent the sum of trends for these cancers as well as diagnostic trends. The decreased incidence observed during the last decade might thus be explained in terms of a combination of improved diagnostic methods to detect primary tumours and decreasing incidence for e.g. pancreatic cancer and lung cancer among males. There is a need of evidence-based programs that define the continuum of care for CUP patients. Such a program is currently being developed through collaboration between all health care regions in Sweden.

New prognostic index to predict survival in patients with cancer of unknown primary site with unfavourable prognosis

AIMS

To identify independent prognostic factors in patients with cancer of unknown primary site (CUP) who do not belong to prognostically favourable subsets, and to develop a prognostic index for predicting survival in these patients.

MATERIALS AND METHODS

In this prospective study, univariate and multivariate analyses of prognostic factors were conducted in a population of 145 patients with CUP in two clinical institutions. Subsets of patients with favourable prognostic features and those requiring well-defined treatment were excluded.

RESULTS

The 1-year overall survival rate for all patients was 42% and the median overall survival was 330 days. Overall survival was significantly related to the following pre-treatment prognostic factors: poor Eastern Cooperative Oncology Group performance status (ECOG PS)>or=2, presence of liver metastasis, elevated serum lactate dehydrogenase (LDH), high white blood cell count, anaemia, age>or=63 years, and prolonged QTc interval in electrocardiography (ECG). In multivariate analysis, four independent adverse prognostic parameters were retained: elevated LDH (hazard ratio 2.21; 95% confidence interval 1.41-3.47; P=0.001), prolonged QTc interval (hazard ratio 2.10; 95% confidence interval 1.28-3.44; P=0.003), liver metastasis (hazard ratio 1.77; 95% confidence interval 1.11-2.81; P=0.016) and ECOG PS>or=2 (hazard ratio 1.69; 95% confidence interval 1.05-2.73; P=0.03). We developed a prognostic index for overall survival based on the following subgroups: good prognosis (no or one adverse factor), intermediate prognosis (two adverse factors) and poor prognosis (three or four adverse factors). The median overall survival for the three subgroups was 420, 152 and 60 days, respectively, P<0.0001.

CONCLUSIONS

This study validated previously identified important prognostic factors for survival in patients with CUP. Prolonged QTc was additionally identified as a strong adverse prognostic factor. We developed a simple prognostic index using performance status, LDH, presence of liver metastasis and QTc interval in ECG, which allowed assignment of patients into three subgroups with divergent outcome.