Management of cancer from an unknown primary

Cancer of Unknown Primary Site: Real Entity or Misdiagnosed Disease?

Metastasis is a late event in the progression of any tumour. However, invasive cancers are occasionally detected in the form of metastatic lesions without a clearly detectable primary tumour. Cancer of unknown primary site (CUP) is defined as a confirmed metastatic tumour, with unknown primary tumour site, despite the standardized diagnostic approach that includes clinical history, routine laboratory tests, and complete physical examination. Due to the lack of basic research on its primary causes, CUP is appropriately termed an 'orphan' cancer. Nevertheless, CUP accounts for 2-5% of diagnosed malignancies. To date, it is unclear whether CUP is an entity with primary dormancy as its hallmark or an entity with genetic abnormalities that cause it to manifest as a primary metastatic disease. In this review, we discuss different aspects of CUP, including its current diagnostic methods, angiogenesis effectors, relationship with cancer stem cells and current treatments.

Subsequent cancers in patients diagnosed with cancer of unknown primary (CUP): etiological insights?

BACKGROUND

Patterns of subsequent malignancies in patients with cancer of unknown primary (CUP) may provide etiological insight into the primary tumor. The objective of the present study is to quantify risks of the subsequent cancers in CUP patients since such studies are lacking.

PATIENTS AND METHODS

A population-based cohort of CUP was identified from the Swedish Family-Cancer Database of year 2008. Standardized incidence ratios (SIRs) were calculated for developing the following malignancies in 31,357 CUP patients from 1975 to 2008.

RESULTS

A total of 755 CUP patients developed subsequent cancers, showing a significantly increased overall SIR of 1.69 (95% confidence interval 1.57-1.81). Among the most common 32 malignancies, increased SIRs were noted for 16 sites. Over 10-fold increases were observed for squamous cell carcinoma at four sites, possibly as a result of uncontrolled human papillomavirus infection due to faltering immune surveillance. The highest SIRs were observed among CUP patients diagnosed at a younger age and during the first follow-up year.

CONCLUSIONS

Swedish CUP survivors had a higher risk of developing many subsequent cancers. Different patterns of risk excess may be suggestive of possible roles for disease- and therapy-related immunosuppression, reappearance of hidden primary tumors, or genetic predisposition.

Cancer of unknown primary site in which tumor marker-oriented chemotherapy was effective and pancreatic cancer was finally confirmed at autopsy

We report a 47-year-old man with cancer of unknown primary site in whom pancreatic cancer was confirmed at autopsy. Although a primary lesion was not confirmed, we planned to perform tumor marker-oriented chemotherapy because pancreatic cancer was suspected as the primary lesion based on tumor markers and pathological findings from metastatic lymph node. Neither S-1 nor gemcitabine was effective. However, gemcitabine combined with low-dose cisplatin therapy resulted in a marked decrease in the size of tumors. Microscopic examination at autopsy revealed poorly differentiated adenocarcinoma in the pancreatic head, although a pancreatic mass was not clear macroscopically.

Death certificates provide an adequate source of cause of death information when evaluating lung cancer mortality: an example from the Mayo Lung Project

To assess the accuracy of death certificates in assigning lung cancer as the underlying cause of death, death certificate data were compared to mortality review committee-determined causes of death among participants in the Mayo Lung Project. Further, the impact of death certificate misclassification on lung cancer mortality rates and Cox proportional hazards models was evaluated. The Mayo Lung Project (1971-1983) was a randomized controlled trial of lung cancer screening; participants were male smokers aged 45 years and older who were seen as outpatients at the Mayo Clinic in Rochester, Minnesota. Overall there were 237 lung cancer deaths according to mortality review, and 224 according to the death certificate (sensitivity 88.6 percent, 95 percent confidence interval (CI) 83.9, 92.4; specificity 99.1 percent, 95 percent CI 98.6, 99.5). As compared to the mortality review committee's determination, the use of death certificate data resulted only in slight decreases to the calculated lung cancer mortality rates for each screening arm, and did not result in appreciable changes to hazard ratios for lung cancer mortality in Cox regression models. In these data, death certificates were sufficiently sensitive and specific such that their use did not result in a meaningful change to mortality-based outcomes.

Multicenter phase-II trial of irinotecan plus oxaliplatin [IROX regimen] in patients with poor-prognosis cancer of unknown primary: a hellenic cooperative oncology group study

BACKGROUND

Cancer of unknown primary (CUP) lacks established therapy although it affects 3% of cancer patients. We evaluated the irinotecan-oxaliplatin combination (IROX regimen) in previously untreated patients with non-favorable subsets of unknown primary carcinomas.

METHODS

This was a multicenter phase-II trial. Protocol treatment consisted of oxaliplatin 80 mg/m(2) followed by irinotecan 160 mg/m(2) administered every 3 weeks. The primary end points were response rate and toxicity, and secondary end points were time to progression and survival.

RESULTS

Forty-seven patients with liver, bone or multiple visceral metastases entered into the trial and received a median 6 chemotherapy cycles (1-11). The regimen was very well tolerated with one febrile neutropenia case and six cases with diarrhea grade 3 (16%). In intent-to-treat analysis the tumor response rate was 13% (95% CI = 4.8-25.7%) and 12 patients (27%, 95%CI 13.9-40.4%) had at least 4 months' duration of disease stabilization. The median time to progression was 2.7 months and the median survival was 9.5 months, with 40% of patients alive at 1 year.

CONCLUSIONS

The IROX regimen demonstrated similar efficacy and a favorable toxicity profile compared to other more toxic chemotherapy combinations in patients with poor-prognosis CUP.