Antecedent therapy versus detection bias as causes of neoplastic multimorbidity

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.

Coupling of prostate and thyroid cancer diagnoses in the United States

BACKGROUND

Prostate and thyroid cancers represent two of the most overdiagnosed tumors in the US. Hypothesizing that patients diagnosed with one of these malignancies were more likely to be diagnosed with the other, we examined the coupling of diagnoses of prostate and thyroid cancer in a large US administrative dataset.

METHODS

The surveillance, epidemiology, and end results (SEER) database was used to identify men diagnosed with clinically localized prostate cancer (CaP) or thyroid cancer between 1995 and 2010. SEER*stat software was used to estimate multivariable-adjusted standardized incidence ratios (SIRs) and investigate the rates of subsequent malignancy diagnosis. Additional non-urologic cancer sites were added as control groups.

RESULTS

Patients with thyroid cancer were much more likely to be diagnosed with CaP than patients in the SEER control group (SIR 1.28 [95% CI 1.1-1.5]; p < 0.05). Similarly, the observed incidence of thyroid cancer was significantly higher in patients with CaP when compared with SEER controls (SIR 1.30 [95% CI 1.2-1.4]; p < 0.05). When stratified by follow-up interval, the observed thyroid cancer diagnosis rate among men with CaP was significantly higher than expected at 2-11 (SIR 1.83 [95% CI 1.4-2.4]), 12-59 (SIR 1.24 [95% CI 1.0-1.5]), and 60-119 (SIR 1.25 [95% CI 1.0-1.5]) months of follow-up. There was no increased risk of CaP or thyroid cancer diagnosis among patients with non-urologic malignancies.

CONCLUSIONS

There is a significant association of diagnoses with prostate and thyroid cancer in the US. In the absence of a known biological link between these tumors, these data suggest that diagnosis patterns for prostate and thyroid malignancies are linked.

Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): explanation and elaboration

Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalisability of its results. Taking into account empirical evidence and theoretical considerations, a group of methodologists, researchers, and editors developed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations to improve the quality of reporting of observational studies. The STROBE Statement consists of a checklist of 22 items, which relate to the title, abstract, introduction, methods, results and discussion sections of articles. Eighteen items are common to cohort studies, case-control studies and cross-sectional studies and four are specific to each of the three study designs. The STROBE Statement provides guidance to authors about how to improve the reporting of observational studies and facilitates critical appraisal and interpretation of studies by reviewers, journal editors and readers. This explanatory and elaboration document is intended to enhance the use, understanding, and dissemination of the STROBE Statement. The meaning and rationale for each checklist item are presented. For each item, one or several published examples and, where possible, references to relevant empirical studies and methodological literature are provided. Examples of useful flow diagrams are also included. The STROBE Statement, this document, and the associated Web site (http://www.strobe-statement.org/) should be helpful resources to improve reporting of observational research.

[Strengthening the reporting of observational studies in epidemiology (STROBE): explanation and elaboration]

Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalisability of its results. Taking into account empirical evidence and theoretical considerations, a group of methodologists, researchers, and editors developed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations to improve the quality of reporting of observational studies. The STROBE Statement consists of a checklist of 22 items, which relate to the title, abstract, introduction, methods, results and discussion sections of articles. Eighteen items are common to cohort studies, case-control studies and cross-sectional studies and four are specific to each of the three study designs. The STROBE Statement provides guidance to authors about how to improve the reporting of observational studies and facilitates critical appraisal and interpretation of studies by reviewers, journal editors and readers. This explanatory and elaboration document is intended to enhance the use, understanding, and dissemination of the STROBE Statement. The meaning and rationale for each checklist item are presented. For each item, one or several published examples and, where possible, references to relevant empirical studies and methodological literature are provided. Examples of useful flow diagrams are also included. The STROBE Statement, this document, and the associated Web site (http://www.strobe-statement.org/) should be helpful resources to improve reporting of observational research.

Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): explanation and elaboration

Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalisability of its results. Taking into account empirical evidence and theoretical considerations, a group of methodologists, researchers, and editors developed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations to improve the quality of reporting of observational studies. The STROBE Statement consists of a checklist of 22 items, which relate to the title, abstract, introduction, methods, results and discussion sections of articles. Eighteen items are common to cohort studies, case-control studies and cross-sectional studies and four are specific to each of the three study designs. The STROBE Statement provides guidance to authors about how to improve the reporting of observational studies and facilitates critical appraisal and interpretation of studies by reviewers, journal editors and readers. This explanatory and elaboration document is intended to enhance the use, understanding, and dissemination of the STROBE Statement. The meaning and rationale for each checklist item are presented. For each item, one or several published examples and, where possible, references to relevant empirical studies and methodological literature are provided. Examples of useful flow diagrams are also included. The STROBE Statement, this document, and the associated Web site (http://www.strobe-statement.org/) should be helpful resources to improve reporting of observational research.

Clinical analysis of multiple primary malignancies in the digestive system: A hospital-based study

AIM: To analyze the characteristics of multiple primary malignancies (MPMs) of digestive system; including incidence, types of tumor combinations, time intervals between development of multiple tumors, clinical course, and prognostic factors affecting survival and mortality.

METHODS: Data from a total of 129 patients treated from January 1991 to December 2000 for pathologically proved MPMs, including at least one originating from the digestive system, were reviewed retrospectively.

RESULTS: Among 129 patients, 120 (93.02%) had two primary cancers and 9 (6.98%) had three primary cancers. The major sites of MPMs of the digestive system were large intestine, stomach, and liver. Associated non-digestive cancers included 40 cases of gynecological cancers, of which 31 were carcinoma of cervix and 10 cases of genitourinary cancers, of which 5 were bladder cancers. Other cancers originated from the lung, breast, nasopharynx, larynx, thyroid, brain, muscle, and skin. Reproductive tract cancers, especially cervical, ovarian, bladder, and prostate cancers were the most commonly associated non-GI cancers, followed by cancer of the lung and breasts. Forty-three cases were synchronous, while the rest (86 cases) were metachronous cancers. Staging of MPMs and treatment regimes correlated with the prognosis between survival and non-survival groups.

CONCLUSION: As advances in cancer therapy bring about a progressively larger percentage of long-term survivors, the proportion of patients with subsequent primary lesions will increase. Early diagnosis of these lesions, based on an awareness of the possibility of second and third cancers, and multidisciplinary treatment strategies will substantially increase the survival of these patients.

Between iatrotropic stimulus and interiatric referral: the domain of primary care research

The "iatrotropic stimulus" is a typical example of Alvan Feinstein's terminology and his clinical way of thinking about medical research. Feinstein specified "interiatric referral" as an additional important factor affecting "the likelihood that patients will appear at the particular setting in which research is being conducted." He emphasized these phenomena as highly relevant for clinical judgment, clinical research, and clinical epidemiology. This has stimulated the realization of original clinical research in international primary medical care. It has helped to recognize the characteristics of the spectrum of health problem and morbidity patterns presented to primary care physicians and to acknowledge the position of generalistic primary care research between open population research and clinical research in referred (specialist) care. Accordingly, primary care-specific challenges in investigating (early) diagnosis, prognosis, treatment, and referral decisions have emerged. This research supports adequate decision-making by the primary care physician, which is important for effective health care. Although Feinstein was a clinical specialist and has always lived in a country without a very strong primary care tradition, he not only recognized the value of primary care research but also substantially contributed to its development.

Comorbidity in operable lung cancer: a multicenter descriptive study on 2992 patients

STUDY OBJECTIVES

To ascertain the frequency of diseases associated (comorbidity) with operable lung cancer (LC) globally, in relation to the presence of neoplastic clinical symptoms and age.

DESIGN

Prospective; multi-institutional of 19 Spanish hospitals.

PATIENTS

Two thousand nine hundred and ninety two consecutive cases of LC, treated surgically by the Bronchogenic Carcinoma Co-operative Group of the Spanish Society of Pneumology and Thoracic Surgery (GCCB-S) between 1993 and 1997, are analysed.

METHODS

At time of treatment, data on the presence or absence of different specific comorbidities in all consecutive patients operated on for LC were entered on identical forms at all hospitals of the GCCB-S.

RESULTS

In 2189 patients (73%) there was one or several comorbidities (chronic obstructive pulmonary disease [COPD], systemic arterial hypertension, previous tumour, cardiac disease, peripheral vascular disease or diabetes). Fifty percent of the LC was associated to COPD; in 32% of these patients with COPD, preoperative measurement of FEV1 was 70% below the theoretical value. In comparing the cases with symptoms ascribable to LC, it was found that in asymptomatic patients the presence of a previous tumour, arterial hypertension or cardiac disease was significantly more frequent. Conversely, in symptomatic patients, COPD was significantly more frequent. The frequency of all evaluated comorbidities is significantly higher in the older age groups.

CONCLUSIONS

In this multicenter study encompassing 2992 patients with operable LC, a high frequency of comorbidity has been found, COPD occurring most frequently. Certain diseases are more prevalent in asymptomatic patients, probably due to a screening bias. In older patients, there was a significant increase of all comorbidities.

Quadruple cancer in a single patient: a report of four cases

Multiple primary neoplasia was once considered a rare curiosity but is now a well recognized phenomenon. Only a few papers have been published in the English literature with regard to occurrence of four or more primary malignancies in a single patient. We report four cases of quadruple cancer; a review of the literature about this topic is discussed.