Power and limits of modern cancer diagnostics: cancer of unknown primary

Survival in Kidney and Bladder Cancers in Four Nordic Countries through a Half Century

Kidney and bladder cancers share etiology and relatively good recent survival, but long-term studies are rare. We analyzed survival for these cancers in Denmark, Finland, Norway (NO), and Sweden (SE) over a 50-year period (1971-2020). Relative 1- and 5-year survival data were obtained from the NORDCAN database, and we additionally calculated conditional 5/1-year survival. In 2016-2020, 5-year survivals for male kidney (79.0%) and bladder (81.6%) cancers were best in SE. For female kidney cancer, NO survival reached 80.0%, and for bladder cancer, SE survival reached 76.1%. The magnitude of 5-year survival improvements during the 50-year period in kidney cancer was over 40% units; for bladder cancer, the improvement was over 20% units. Survival in bladder cancer was worse for women than for men, particularly in year 1. In both cancers, deaths in the first year were approximately as many as in the subsequent 4 years. We could document an impressive development for kidney cancer with tripled male and doubled female 5-year survival in 50 years. Additionally, for bladder cancer, a steady improvement was recorded. The current challenges are to curb early mortality and target treatment to reduce long-term mortality.

Long-term survival trends in solid cancers in the Nordic countries marking timing of improvements

Survival studies are an important indicator of the success of cancer control. We analyzed the 5-year relative survival in 23 solid cancers in Denmark, Finland, Norway and Sweden over a 50-year period (1970-2019) at the NORDCAN database accessed from the International Agency for Research on Cancer website. We plotted survival curves in 5-year periods and showed 5-year periodic survival. The survival results were summarized in four groups: (1) cancers with historically good survival (>50% in 1970-1974) which include melanoma and breast, endometrial and thyroid cancers; (2) cancers which constantly improved survival at least 20% units over the 50 year period, including cancers of the stomach, colon, rectum, kidney, brain and ovary; (3) cancer with increase in survival >20% units with changes taking place in a narrow time window, including oral, oropharyngeal, testicular and prostate cancers; (4) the remaining cancers with <20% unit improvement in survival including lung, esophageal, liver, pancreatic, bladder, soft tissue, penile, cervical and vulvar cancers. For cancers in groups 1 and 2, the constant development implied multiple improvements in therapy, diagnosis and patient care. Cancers in group 3 included testicular cancers with known therapeutic improvements but for the others large incidence changes probably implied that cancer stage (prostate) or etiology (oropharynx) changed into a more tractable form. Group 4 cancers included those with dismal survival 50 years ago but a clear tendency upwards. In 17 cancers 5-year survival reached between 50% and 100% while in only six cancers it remained at below 50%.

Survival trends in solid cancers in the Nordic countries through 50 years

AIMS

Global survival studies in cancer have generally shown favourable development, but studies over extended periods on populations for which medical care is essentially free of charge are lacking.

METHODS

We analyse relative 1- and 5-year survival in all solid cancers in Denmark, Finland, Norway and Sweden through a 50-year period (1970-2019) using the NORDCAN database.

RESULTS

The most recent survival results showed three types of patterns. Cancers of very good survival (5-year survival ∼90%) included common cancers of the breast and prostate, as well as melanoma. The second pattern, which included the largest number of cancers, showed 1-year survival of over 80% and a drop of 10-20 % units in 5-year survival. The third group consisted of eight fatal cancers, sharing poor 5-year survival (around 20%). The 50-year improvement in 1-year survival was largest (30-50 % units) in kidney, brain, gallbladder and liver cancers, and (∼30%) in colon, small intestinal, lung, pleural, pancreas and ovarian cancers. Improvements in 5-year survival were highest (40-50 % units) in prostate and kidney cancers but remained at 10-20 % units for the eight fatal cancers. Survival showed significant sex preferences for a few cancers.

CONCLUSIONS

The analysis over a half-century confirms the progress in 'real-world' cancer control, and in 84% of patients 5-year survival was &gt;60%. Metastases remain a challenge, placing the emphasis on early detection before metastasis occurs. Novel therapies, such as immunotherapy which has curative potential even against metastatic disease, are needed.

Cancer-of-Unknown-Primary-Origin: A SEER-Medicare Study of Patterns of Care and Outcomes among Elderly Patients in Clinical Practice

Simple Summary

Cancer-of-unknown-primary-origin (CUP) is challenging to diagnose and treat, and little is known about its diagnostic work-up, treatment, and outcomes in routine healthcare. We examined data from elderly patients (at least 66 years old) diagnosed with CUP in real-world US clinical practice, using the Surveillance, Epidemiology, and End Results–Medicare-linked database. Only half of elderly patients with CUP received all three diagnostic work-up procedures (biopsy, immunohistochemistry, and imaging), as recommended by guidelines. Patients who received all three diagnostic work-up procedures were more likely to receive any type of anticancer treatment, and patients who did not receive full diagnostic work-up had shorter median overall survival, particularly with increasing age. Overall, these results suggest that further studies are needed to understand why many patients given a diagnosis of CUP do not receive complete diagnostic work-up or treatment. Further research into improving diagnostic work-up and treatment effectiveness in patients diagnosed with CUP is required.

Abstract

Knowledge of contemporary patterns of cancer-of-unknown-primary-origin (CUP) diagnostic work-up, treatment, and outcomes in routine healthcare is limited. Thus, we examined data from elderly patients diagnosed with CUP in real-world US clinical practice. From the Surveillance, Epidemiology, and End Results–Medicare-linked database, we included patients ≥ 66 years old with CUP diagnosed between 1 January 2013 and 31 December 2015. We analyzed baseline demographics, clinical characteristics, methods of diagnostic work-up (biopsy, immunohistochemistry, imaging), treatment-related factors, and survival. CUP diagnosis was histologically confirmed in 2813/4562 patients (61.7%). Overall, 621/4562 (13.6%) patients received anticancer pharmacotherapy; among these, 97.3% had a histologically confirmed tumor and 83.1% received all three procedures. Among those with a histologically confirmed tumor, increasing age, increasing comorbidity score, not receiving all three diagnostic measures, and having a not-further specified histologic finding of only ‘malignant neoplasm’ were all negatively associated with receipt of anticancer pharmacotherapy. Median overall survival was 1.2 months for all patients. Median time between CUP diagnosis and treatment initiation was 41 days. Limited diagnostic work-up was common and most patients did not receive anticancer pharmacotherapy. The poor outcomes highlight a substantial unmet need for further research into improving diagnostic work-up and treatment effectiveness in CUP.

Progress in survival in renal cell carcinoma through 50 years evaluated in Finland and Sweden

Global survival studies have shown favorable development in renal cell carcinoma (RCC) treatment but few studies have considered extended periods or covered populations for which medical care is essentially free of charge. We analyzed RCC survival in Finland and Sweden over a 50-year period (1967-2016) using data from the NORDCAN database provided by the local cancer registries. While the health care systems are largely similar in the two countries, the economic resources have been stronger in Sweden. In addition to the standard 1- and 5-year relative survival rates, we calculated the difference between these as a measure of how well survival was maintained between years 1 and 5. Relative 1- year survival rates increased almost linearly in both countries and reached 90% in Sweden and 80% in Finland. Although 5-year survival also developed favorably the difference between 1- and 5-year survival rates did not improve in Sweden suggesting that the gains in 5-year survival were entirely due to gains in 1-year survival. In Finland there was a gain in survival between years 1 and 5, but the gain in 1-years survival was the main contributor to the favorable 5-year survival. Age group specific analysis showed large survival differences, particularly among women. Towards the end of the follow-up period the differences narrowed but the disadvantage of the old patients remained in 5-year survival. The limitations of the study were lack of information on performed treatment and clinical stage in the NORDCAN database. In conclusion, the available data suggest that earlier diagnosis and surgical treatment of RCC have been the main driver of the favorable change in survival during the past 50 years. The main challenges are to reduce the age-specific survival gaps, particularly among women, and push survival gains past year 1.

Design of a New Peptide Substrate Probe of the Putative Biomarker Legumain with Potential Application in Prostate Cancer Diagnosis Ex Vivo

The lysosomal endoprotease legumain (asparaginyl endoprotease) has been proposed as a putative biomarker in prostate tumours, in which the enzyme is markedly overexpressed. Overexpression, coupled with highly selective specificity for cleavage of substrates at the C-terminus of asparagine (Asn) residues, make legumain an attractive biochemical target for potential diagnosis, prognosis and treatment. We report the design, synthesis, characterisation and preliminary evaluation of a new rhodamine-B (Rho-B)-labelled legumain peptide substrate probe5[Rho-Pro-Ala-Asn-PEG-AQ(4-OH)] and its selective targeting to lysosomes in PC3 prostate cancer cells. Probe5was efficiently activated by recombinant human legumain to afford the high quantum yield reporter fluorophore tripeptide4b(Rho-Pro-Ala-Asn-OH) with concomitant release of intense fluorescence. Furthermore, probe5was activated upon incubation with homogenates derived from fresh-frozen tissue material of prostatectomy specimens. Probe5represents a new viable biochemical tool for probing the activity of legumain with the potential to be used in ex vivo diagnostics in the cancer pathology laboratory.

Advances in the management of brain metastases from cancer of unknown primary

Cancer of unknown primary accounts for 3-5% of all cancers for which an adequate investigation does not identify the primary tumor. The particular subset of brain metastasis in cancer of unknown primary (BMCUP) is a clinical challenge that lacks standardized diagnostic and therapeutic options. It is diagnosed predominantly in male patients in the sixth decade of age with complaints of headache, neurological dysfunction, cognitive and behavioral disturbances and seizures. The therapeutic approach to patients with BMCUP relies on local control and systemic treatment. Surgery or stereotactic radiosurgery and/or whole brain radiation therapy seems to be the cornerstone of the treatment approach to BMCUP. Systemic therapy remains essential as cancers of unknown primary are conceptually metastatic tumors. The benefits of chemotherapy were disappointing whereas those of targeted therapies and immune checkpoint inhibitors remain to be evaluated. In this Review, we address the advances in the diagnosis and treatment of BMCUP.

18F-fluorodeoxyglucose positron emission tomography/computed tomography in carcinoma of unknown primary: A subgroup-specific analysis based on clinical presentation

The aim of this study was to explore the clinical efficacy of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in tumor detection in patients with proven or suspected carcinoma of unknown primary origin (CUP) and making a subgroup-specific analysis. This was a retrospective, cross-sectional survey of patients with CUP syndrome who were referred for ¹⁸F-FDG PET-CT studies over a 2-year period. FDG-PET-CT scans were performed in compliance with the standard whole-body protocol, i.e., at least 6 h of fasting and were carried out with injected FDG radioactivity dose between 259 MBq and 370 MBq. The time from FDG injection to PET data acquisition was between 60 and 90 min. PET/CT scanning was acquired from the skull base to the upper third of the thighs. Nonenhanced, low-dose attenuation correction CT (110/70 kV/mAs) was performed for all patients. Twenty-one patients of clinically designated with CUP (male:female = 7:14; age range: 42–70 years; mean age: 57.95 years) fulfilling the inclusion criteria were enrolled in this analysis. The patients were subdivided into two groups: A - Those with histopathological proof (n = 12); B - Those with clinical/tumor markers/radiological suspicion of malignancy (n = 9). Among the first group, the sites of metastases in decreasing order of frequency were lymph nodes (n = 9/20; 75%), brain (n = 2; 16.67%), and liver (n = 1; 8.33%). In group B, six patients (66.7%) presented with hypodense/enhancing lesions in the brain and three (33.3%) had altered marrow signal intensity of spine. Overall, hypermetabolic lesions on FDG-PET/CT indicating the primary tumor sites were identified in 14 patients (66.7%). Twelve out of 14 primary sites were subsequently proven by histopathology, whereas two patients with biopsy-proven metastatic lesions in brain, with suspicious primary site in lung had been corroborated by FDG-PET/CT revealing multiple other metastatic sites, were not biopsied and were subsequently enrolled for palliative chemotherapy. When the results were examined individually in each of the Group A and Group B, the primary tumor detection rate was 58.3% and 77.7%, respectively. The identified primary tumor sites were lung 9/14 (64.4%), uterus/cervi 2/14 (14.3%), breast 1/14 (7.1%), esophagus 1/14 (7.1%), and aryepiglottic fold 1/14 (7.1%). In conclusion, FDG-PET/CT is not only helpful in histologically proven cases of CUP (irrespective of the metastatic sites), this modality also demonstrates high tumor detection rate in patients with clinical/radiological suspicion of malignancy. Being a whole body technique, it can additionally aid in disease staging in these patients which could be potentially helpful in their clinical management.

Familial risks in and between stone diseases: sialolithiasis, urolithiasis and cholelithiasis in the population of Sweden

BACKGROUND

According to the literature the three stone diseases, sialolithiasis (SL), urolithiasis (UL) and cholelithiasis (CL) share comorbidities. We assess familial and spouse risks between these stone disease and compare them to familial risks for concordant (same) stone disease.

METHODS

Study population including familiar relationships was obtained from the Swedish Multigeneration Register and stone disease patients were identified from nation-wide medical records. Standardized incidence ratios (SIRs) were calculated for 0-83 year old offspring when their first-degree relatives were diagnosed with stone disease and the rates were compared to individuals without a family history of stone disease. Numbers of offspring with SL were 7906, for UL they were 170,757 and for CL they were 204,369.

RESULTS

SIRs for concordant familial risks were 2.06 for SL, 1.94 for UL and 1.82 for CL. SIRs for SL and UL were slightly higher for women than for men. Familial risks between stone diseases were modest. The highest risk of 1.17 was for UL when family members were diagnosed with CL, or vice versa. The SIR for UL was 1.15 when family members were diagnosed with SL. Familial risks among spouses were increased only for UL-CL pairs (1.10).

CONCLUSIONS

Familial risks for concordant SL were 2.06 and marginally lower for the other diseases. Familial risks between stone diseases were low but higher than risks between spouses. The data show that familial clustering is unique to each individual stone disease which would imply distinct disease mechanisms. The results cast doubt on the reported comorbidities between these diseases.

Small-Molecule Lanthanide Complexes Probe for Second Near-Infrared Window Bioimaging

Over the past few years, significant efforts have been made to create new fluorescent probes operating at longer wavelengths, particularly in the second near-infrared (NIR-II) window from 1000 to 1700 nm, offering enhanced tissue penetration compared to light in the visible and first near-infrared window (700-900 nm). However, most of the reported NIR-II fluorophores meet such dilemmas; they are excreted slowly and largely retained within the reticuloendothelial system. Here, we report a rapidly excreted NIR-II lanthanide complex Nd-DOTA (over 50% excreted through the kidneys within 3 h postinjection) with a molecular mass only 0.54 kDa. The NIR-II imaging quality of Nd-DOTA was far superior to that of clinically approved ICG with good photostability and deep tissue penetration (7 mm). Superior tumor-to-normal tissue ratio was successfully achieved to facilitate the abdominal ovarian metastases surgical delineation. Metastases with ≤1 mm can be completely excised under NIR-II bioimaging guidance. Significantly, since the Nd-DOTA structure is same to the clinically approved magnetic resonance imaging (MRI) contrast Gd-DOTA, it will speed up the clinical translation for this novel kind of NIR-II probes in the future.

Surveillance Bias in Cancer Risk After Unrelated Medical Conditions: Example Urolithiasis

We analysed cancer risks in patients with urinary tract stones but some features of the generated results alarmed us about possible surveillance bias, which we describe in this report. We used nationwide Swedish hospital records to identify patients with urinary tract stones (N = 211,718) and cancer registration data for cancer patients for years 1987 to 2012. Standardized incidence ratios (SIRs) for cancer were calculated after the last medical contact for urinary tract stones. All cancers were increased after kidney (SIR 1.54, 95%CI: 1.50–1.58), ureter (1.44, 1.42–1.47), mixed (1.51, 1.44–1.58) and bladder stones (1.63, 1.57–1.70). The risk of kidney cancer was increased most of all cancers after kidney, ureter and mixed stones while bladder cancer was increased most after bladder stones. All SIRs decreased steeply in the course of follow-up time. Tumour sizes were smaller in kidney cancer and in situ colon cancers were more common in patients diagnosed after urinary tract stones compared to all patients. The results suggest that surveillance bias influenced the result which somewhat surprisingly appeared to extend past 10 years of follow-up and include cancers at distant anatomical sites. Surveillance bias may be difficult to avoid in the present type of observational studies in clinical settings.

Diagnostic Accuracy of 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in the Evaluation of Carcinoma of Unknown Primary

Objective:

Detection of primary tumor site in patients with carcinoma of unknown primary (CUP) syndrome has always been a diagnostic dilemma, necessitating extensive workup. Early detection of primary tumor site coupled with specific therapy improves prognosis. The low detection rate of the primary tumor site can be attributed to the biological behavior or the small size of the primary tumor to be detected by conventional imaging. The objective of this study was to evaluate the diagnostic accuracy of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography (PET-CT) in detecting CUP.

Methods:

A retrospective, cross-sectional analysis of 100 PET-CT scans of patients with CUP syndrome between November 2009 and December 2013 was performed. Eighteen patients whose final histopathology results could not be obtained for correlation were excluded from analysis. The hypermetabolic sites were assessed in correlation with histopathology. The diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive values were assessed for PET-CT.

Results:

Out of the 82 patients, primary tumor was correctly identified in 57.3% patients by ¹⁸F-FDG PET-CT (true positive). The PET-CT scan results were negative for primary site localization in 15% of patients (false negative). While 21% had true negative results, 7.3% displayed false positive results. PET-CT scan upstaged the disease in 27% cases. Overall, the diagnostic accuracy was found to be 78%, sensitivity 80%, specificity 74%, positive predictive value 88.7% and negative predictive value 59%.

Conclusion:

Our data supports the utility of ¹⁸F-FDG PET-CT scan in the localization and staging of CUP syndrome.

Cost-effectiveness of using a gene expression profiling test to aid in identifying the primary tumour in patients with cancer of unknown primary

We aimed to investigate the cost-effectiveness of a 2000-gene-expression profiling (GEP) test to help identify the primary tumor site when clinicopathological diagnostic evaluation was inconclusive in patients with cancer of unknown primary (CUP). We built a decision-analytic-model to project the lifetime clinical and economic consequences of different clinical management strategies for CUP. The model was parameterized using follow-up data from the Manitoba Cancer Registry, cost data from Manitoba Health administrative databases and secondary sources. The 2000-GEP-based strategy compared to current clinical practice resulted in an incremental cost-effectiveness ratio (ICER) of $44,151 per quality-adjusted life years (QALY) gained. The total annual-budget impact was $36.2 million per year. A value-of-information analysis revealed that the expected value of perfect information about the test's clinical impact was $4.2 million per year. The 2000-GEP test should be considered for adoption in CUP. Field evaluations of the test are associated with a large societal benefit.

A Case of Gingival Metastasis from Rectal Cancer in Which Immunohistochemistry and PET-CT Were Useful for the Diagnostic Procedure

A 50-year-old man was referred to our hospital because of a 2-month history of painful gingival swelling. Histopathological examination of the biopsy specimen showed a metastatic adenocarcinoma, and a chest-abdominopelvic CT showed multiple metastases in the lung, liver, and spleen, but failed to demonstrate the primary tumor. He had never complained of abdominal symptoms, and physical examination did not show any abnormality in the abdomen. However, immunohistochemical staining including caudal-related homeobox transcription factor (CDX-2) of the gingival tumor and PET-CT findings strongly suggested colorectal cancer as the origin. Colonoscopy then revealed a tumor in the rectum, and systemic chemotherapy was started immediately.

An intracellularly activatable, fluorogenic probe for cancer imaging

A newly designed, dual-functional probe based on intracellular activation has been successfully developed for the detection of cancer cells.

Second primary cancers after cancer of unknown primary in Sweden and Germany: efficacy of the modern work-up

In unsparing efforts to find the hidden primaries, second primary cancers (SPCs) unrelated to cancer of unknown primary (CUP) are found. The detection rates of SPCs after CUP can be considered as measures for the effectiveness of modern diagnostic techniques in finding tumors. We aimed to compare the rates of specific SPCs found after the work-up of CUP and the more sign/symptom-directed diagnostic approaches applied after any other cancer. The number of CUP patients identified in the nationwide Swedish database and nine German cancer registries was 24 641 from 1997 through 2006, and rate ratios (RRs) for SPCs were recorded in two follow-up periods. The detection rate of SPCs immediately after any other cancer was about two times higher in Germany than in Sweden, but the rate immediately after CUP was almost the same for the two datasets. In the joint analyses after CUP, the RRs of liver, lung, breast, and kidney cancers were higher than after any other cancer, whereas the RRs of prostate, urinary bladder, and connective tissue cancers as well as non-Hodgkin's lymphoma were not significantly different; the RR of cancers of upper aerodigestive tract was lower after CUP than after any other cancer. The joint data indicate that the work-up is efficient in detecting tumors in the thoracoabdominal organs that are screened by computed tomography. For some other organ sites, the more sign/symptom-directed diagnostic approaches may be equally efficient. However, none of the applied techniques could detect all tumors immediately after the first diagnosis.

Time trends in survival from cancer of unknown primary: small steps forward

BACKGROUND

Cancer of unknown primary (CUP) is a fatal cancer for which incidence trends have changed but detailed survival trends remain unexplored. These could point out successful diagnostic and therapeutic approaches. We investigate survival trends in CUP according to histology, locations of metastases and site-specific causes of death.

PATIENTS AND METHODS

A total of 20,523 CUP patients with nodal and extranodal metastases were identified from the Swedish Cancer Registry. Hazard ratios (HRs) were estimated, comparing three different time periods (1987-1993, 1994-2000 and 2001-2008) with respect to histological subtype, CUP location and the cause of death.

RESULTS

Survival for patients with CUP increased over the study period (HR=0.91 [95% confidence interval (CI): 0.78-0.84], p<0.001 for trend). Adenocarcinoma was the only histology associated with increased survival (0.78 [0.74-0.82], p<0.001 for trend). Survival was improved most clearly for CUP of the pelvis (0.55 [0.36-0.83]), peritoneum (0.58 [0.53-0.65]) and nervous system (0.46 [0.29-0.72]). Survival improved substantially in patients with ovarian (0.57 [0.46-0.70]), peritoneal (0.39 [0.24-0.65]) and biliary system cancers (0.67 [0.52-0.87]). Kaplan-Meier curves showed significant survival gains for all CUP and adenocarcinoma patients (p<0.001).

CONCLUSIONS

Over time, survival for patients with CUP increased for adenocarcinoma and for CUP of the pelvis, peritoneum and nervous system. Survival trends in CUP may be related to (1) similar trends in other common metastatic tumours, particularly pancreatic and hepatobiliary cancers, which are common 'hidden' primaries for CUP, (2) earlier detection and (3) advances in the management of metastatic cancers. The improvement in survival at specific locations suggests true therapeutic gains.

Site-specific cancer deaths in cancer of unknown primary diagnosed with lymph node metastasis may reveal hidden primaries

Cancer of unknown primary site (CUP) is a fatal cancer ranking among the five most common cancer deaths. CUP is diagnosed through metastases, which are limited to lymph nodes in some patients. Cause-specific survival data could guide the search for hidden primary tumors and help with therapeutic choices. The CUP patients were identified from the Swedish Cancer Registry between 1987 and 2008; 1,444 patients had only lymph node metastasis of defined histology (adenocarcinoma, squamous cell or undifferentiated). Site-specific cancer deaths were analyzed by lymph node location and histology. Kaplan-Meier survival curves were compared with metastatic primary cancer at related sites. Among the patients with metastasis to head and neck lymph nodes, 117 (59.1% of the specific cancer deaths) died of lung tumors. Patients with axillary lymph node metastasis died of lung and breast tumors in equal proportions (40.2% each). Also, squamous cell CUP in head and neck lymph nodes was mainly associated with lung tumor deaths (53.1%). With a few exceptions, survival of CUP patients with lymph node metastasis was indistinguishable from survival of patients with metastatic primary cancer originating from the organs drained by those nodes. The association between lymph node CUP metastases with cancer deaths in the drained organ and the superimposable survival kinetics suggests that drained organs host hidden primaries. Importantly, half of all site-specific cancer deaths (266/530) were due to lung tumors. Thus, an intense search should be mounted to find lung cancer in CUP patients with lymph node metastases.

Cancer of unknown primary (CUP): does cause of death and family history implicate hidden phenotypically changed primaries?

BACKGROUND

Cancer of unknown primary (CUP) is diagnosed at the metastatic stage. We aimed to identify hidden primary cancers in CUP patients by comparison with cancers in family members. We take use of the fact that the cause of death in CUP patients is often coded as the cancer in the organ of fatal metastasis.

PATIENTS AND METHODS

Forty-one thousand five hundred and twenty-three CUP patients were identified in the Swedish Family-Cancer Database, and relative risks (RRs) were calculated for cancer in offspring when family members were diagnosed with CUP and died of the cancer diagnosed in offspring.

RESULTS

The RR for lung cancer in offspring was 1.85 when a family member was diagnosed with CUP and died of lung cancer. Significant familial associations were found for seven other cancers. Many familial associations were also significant when offspring CUP patients died of the cancer diagnosed in family members.

CONCLUSIONS

The cause of death after CUP diagnosis frequently matched the cancer found in a family member, suggesting that the CUP had originated in that tissue. The metastasis had probably undergone a phenotypic change, complicating pathological tissue assignment. These novel data suggest that some CUP cases are phenotypically modified primary cancers rather than cancers of unknown primaries.

Survival in cancer of unknown primary site: population-based analysis by site and histology

BACKGROUND

Cancer of unknown primary (CUP) is diagnosed at a metastatic stage, conferring an unfavorable prognosis. The natural history of the disease is poorly understood, which complicates diagnosis, treatment and follow-up. Population-based survival data are lacking regarding location and histology of metastases.

PATIENTS AND METHODS

From the Swedish Cancer Registry, 18 911 CUP patients were identified between years 1987 and 2008. Survival was analyzed by Kaplan-Meier survival curves and Cox regression.

RESULTS

Adenocarcinoma accounted for 70% of all extranodal cases with a 12-month survival of 17% and the median survival of 3 months. Adenocarcinoma was also the most common histology (33.4%) when metastases were limited to lymph nodes, with a 12-month survival of 41% and median survival of 8 months. For extranodal metastases, the extremes in survival were small intestinal cancer with poor prognosis and mediastinal cancer with favorable prognosis. For nodal metastases, patients affected in the head and neck, axillary and inguinal regions had the best prognosis and those with abdominal and intrapelvic metastases the worst prognosis.

CONCLUSIONS

The present data underline the importance of histology and location of metastasis in assisting clinical decision making: hazard ratios differed by a factor of five among extranodal and nodal metastases.