Familial cancer in the general population

Specifying exposure classification parameters for sensitivity analysis: family breast cancer history

One of the challenges to implementing sensitivity analysis for exposure misclassification is the process of specifying the classification proportions (eg, sensitivity and specificity). The specification of these assignments is guided by three sources of information: estimates from validation studies, expert judgment, and numerical constraints given the data. The purpose of this teaching paper is to describe the process of using validation data and expert judgment to adjust a breast cancer odds ratio for misclassification of family breast cancer history. The parameterization of various point estimates and prior distributions for sensitivity and specificity were guided by external validation data and expert judgment. We used both nonprobabilistic and probabilistic sensitivity analyses to investigate the dependence of the odds ratio estimate on the classification error. With our assumptions, a wider range of odds ratios adjusted for family breast cancer history misclassification resulted than portrayed in the conventional frequentist confidence interval.

An Acute Leukaemia Masquerading as Immune Thrombocytopaenic Purpura (ITP)? A Case Report

This is a case report of a 35 year old female with diagnosed Immune Thrombocytopaenic Purpura (ITP) that was strangely followed by acute myeloid leukaemia at 10 months post diagnosis of ITP. She was managed as ITP using prednisolone 45 mg daily for 10 months with good response. She also synchronously carried a pregnancy to term and safe delivery. Shortly after delivery, she represented with gingival bleeding and peripheral film review and subsequent bone marrow cytology was in keeping with AML-M4 subtype. She died shortly after diagnosis without being able to receive chemotherapy.

Clustering of cancer among families of cases with Hodgkin Lymphoma (HL), Multiple Myeloma (MM), Non-Hodgkin's Lymphoma (NHL), Soft Tissue Sarcoma (STS) and control subjects

Background

A positive family history of chronic diseases including cancer can be used as an index of genetic and shared environmental influences. The tumours studied have several putative risk factors in common including occupational exposure to certain pesticides and a positive family history of cancer.

Methods

We conducted population-based studies of Hodgkin lymphoma (HL), Multiple Myeloma (MM), non-Hodgkin's Lymphoma (NHL), and Soft Tissue Sarcoma (STS) among male incident case and control subjects in six Canadian provinces. The postal questionnaire was used to collect personal demographic data, a medical history, a lifetime occupational history, smoking pattern, and the information on family history of cancer. The family history of cancer was restricted to first degree relatives and included relationship to the index subjects and the types of tumours diagnosed among relatives. The information was collected on 1528 cases (HL (n = 316), MM (n = 342), NHL (n = 513), STS (n = 357)) and 1506 age ± 2 years and province of residence matched control subjects. Conditional logistic regression analyses adjusted for the matching variables were conducted.

Results

We found that most families were cancer free, and a minority included two or more affected relatives. HL [(OR_adj (95% CI) 1.79 (1.33, 2.42)], MM (1.38(1.07, 1.78)), NHL (1.43 (1.15, 1.77)), and STS cases (1.30(1.00, 1.68)) had higher incidence of cancer if any first degree relative was affected with cancer compared to control families. Constructing mutually exclusive categories combining "family history of cancer" (yes, no) and "pesticide exposure ≥10 hours per year" (yes, no) indicated that a positive family history was important for HL (2.25(1.61, 3.15)), and for the combination of the two exposures increased risk for MM (1.69(1.14,2.51)). Also, a positive family history of cancer both with (1.72 (1.21, 2.45)) and without pesticide exposure (1.43(1.12, 1.83)) increased risk of NHL.

Conclusion

HL, MM, NHL, and STS cases had higher incidence of cancer if any first degree relative affected with cancer compared to control families. A positive family history of cancer and/or shared environmental exposure to agricultural chemicals play an important role in the development of cancer.

Family history and the risk of breast cancer: a systematic review and meta-analysis

An increased risk of breast cancer in women with a family history of breast cancer has been demonstrated by many studies using a variety of study designs. However, the extent of this risk varies according to the nature of the family history (type of relative affected, age at which relative developed breast cancer and number of relatives affected) and may also vary according to age of the individual. The aim of our study was to identify all the published studies which have quantified the risk of breast cancer associated with a family history of the disease, and to summarise the evidence from these studies, with particular emphasis on age-specific risks according to subject and relative age. Seventy-four published studies were identified. The pooled estimate of relative risk (RR) associated with various family histories was as follows: any relative, RR = 1.9 (95% CI, 1.7-2.0); a first-degree relative, RR = 2.1 (CI = 2.0, 2.2); mother, RR = 2.0 (CI = 1.8, 2.1); sister, RR = 2.3 (CI = 2.1, 2.4); daughter, RR = 1.8 (CI = 1.6, 2.0); mother and sister, RR = 3.6 (CI = 2.5, 5.0); and a second-degree relative, RR = 1.5 (CI = 1.4, 1.6). Risks were increased in subjects under age 50 and when the relative had been diagnosed before age 50.

Family history-related risk of gastric cancer in Japan: a hospital-based case-control study

In Japan, there have been a few reports on the familiar factors of gastric cancer (GC) and on the GC risk related to family history (FH) at other cancer sites. We analyzed the association between GC occurrence and a positive FH of cancer of the stomach and of other sites in a hospital-based case-control study. The subjects included cases histologically confirmed as incident cancer of the stomach (n = 136; 86 male and 50 female patients) and sex and age (+/- 1 year)-matched controls. GC risk was high when a subject had a parental history of GC [Mantel-Haenszel odds ratio adjusted for sex and age (OR)=2.3; 95% confidence interval (95% CI):1.1-5.0]. GC risk was almost unity for a cancer FH of any other cancer site, even among closer relatives, suggesting little or no contribution to GC occurrence. The familial occurrence of GC found in this study suggests the existence of a genetic susceptibility to cancer of the stomach. Further, females tended to show higher GC risks than males, when reporting an affected mother (OR=6.0; 95% CI:1.1-31.4 and OR= 1.4; 95% CI:0.4-4.8, respectively), whereas males showed a slightly higher risk than females when reporting an affected father (OR=2.4; 95% CI:0.8-7.5 and OR=2.3; 95% CI:0.4-15.6, respectively). This suggests a possible gender difference in how environmental factors influence GC occurrence. The development of gastric tumors seems to be due to a complex and unknown interaction between environmental and genetic factors.

Mammography and physician breast exams after the diagnosis of breast cancer in a twin or non-twin sister

Reports of breast-cancer-screening behavior were collected from 591 twin sisters of women with breast cancer and 182 non-twin sisters of the same women, and compared with the patterns found by national surveys. Timeline plots indicate that prior to the diagnosis of breast cancer in a sister, these women were being screened at prevailing rates. In the year after diagnosis, the annual frequency of use by them of both mammograms and physician breast exams increased by approximately 25 percent, but in subsequent years these rates dropped to a plateau no more than 10 to 15 percent higher than the baseline. The sisters over age 60 were screened with unusually low frequency, as were those with no partner in the home, those with no regular source of medical care, and especially the siblings of cases that died soon after the diagnosis. The relatively infrequent adoption of a long-term, annual, screening pattern in the face of certain knowledge of personal high risk gives cause for concern about the effectiveness of any intervention program requiring recognition of personal high risk for effectiveness. One cause for optimism is that higher screening rates prevail among those with co-twins diagnosed since 1980, suggesting that the increase in publicity and public education in recent decades has had a beneficial impact.

Is colonoscopic screening appropriate in asymptomatic patients with family history of colon cancer?

Colonoscopy has been advocated by some investigators as the most appropriate means of screening asymptomatic patients with a positive family history of colorectal cancer. However, results of such screening have been widely disparate. The purpose of this study was to evaluate the yield of colonoscopy in a cohort of completely asymptomatic individuals with one or two first-degree relatives with a history of colorectal cancer and to compare this yield with that of colonoscopy in a group of patients with apparent anal bleeding. Patients with possible genetic disorders, such as familial polyposis, were excluded. A total of 160 asymptomatic patients and a comparison group of 137 patients with nonacute anorectal bleeding underwent colonoscopy. Colonoscopy was completed in 143 of the 160 study patients (89 percent) and in all of the comparison patients and did not result in any complications. Twenty-two adenomas were found in 17 study patients (10.6 percent); 16 of the 22 adenomas were less than 1 cm in size. In the comparison group, eight adenomas were identified (5.8 percent of patients). No cancers were identified. The difference in polyp frequency between groups was not significant. The relatively low yield of colorectal neoplasms discovered at colonoscopy in this study may in part be due to the small sample size or to the strict criteria used to define these asymptomatic patients but does not lend strong support to the notion that colonoscopy is an appropriate first step in screening the asymptomatic patient with one or two first-degree relatives with colon cancer.

Clustering of cancer in families of patients with primary lung cancer

We have previously shown that patients with a positive family history of lung cancer did not exhibit characteristics expected if the familial association was a surrogate for a genetic mechanism which was absent in those without such a history. In this study, we examine the incidence of cancer (all sites) in two groups of families: (a) those ascertained through a patient with primary lung cancer (n = 359 families) and (b) through a community control subject (n = 234). The index subjects were excluded from all incidence data analyses. Most families (62 vs 57%) reported at least one member with a history of neoplastic disease. Patients' families were more likely to have 2 or more affected members (p less than 0.05), to exhibit a multigenerational pattern (33 vs 24%) and to have a higher risk of multiple tumours (OR = 1.5) in the same individual. However, most of the sites with the highest odds ratios (males, vocal cord/esophagus 8.3; colon/rectum 2.3; lung 1.96; females, pancreas 4.8; vocal/cord esophagus 4.1; lung 1.8) are smoking associated although these were not necessarily the most frequently affected sites. In conclusion, these data support an ecogenetic etiology of cancer within families.

Oral squamous cell carcinoma in identical twins: report of a case

This case report describes two middle-aged identical female twins with a mild to moderate history of tobacco and alcohol abuse who developed squamous cell carcinomas in the same anatomic sites. By exclusion of major factors, a correlation between heredity and the incidence of cancer in these cases appears likely; however, carcinogenic agents (tobacco and alcohol) must also be considered as contributing factors. Close observation of siblings (and certainly twins) is recommended when head and neck carcinoma occurs prior to middle age. Although no genetic population prone to oral cancer is known, the disease is rare enough in younger individuals to raise the question of a possible genetic predisposition.

Colonoscopic screening of persons with suspected risk factors for colon cancer. I. Family history

A family history of colorectal cancer is believed to place persons at increased risk for development of the disease. It is unclear, however, how "strong" a family history must be to increase this risk or to make colonoscopic screening appropriate. We performed initial colonoscopy in 154 asymptomatic subjects whose only suspected risk factor was one or two first-degree relatives with colorectal cancer; 48 of these subjects also had affected second- and third-degree relatives. We found 45 adenomas in 28 subjects (18%). One subject had a 3-cm villous adenoma. In 6 subjects, the most advanced findings were tubular adenomas 5-9 mm in diameter; in 21 subjects, we found only tubular adenomas that were 2-4 mm in diameter. The prevalence of adenomas increased significantly with age of subjects (p less than 0.01). Although the overall prevalence of colorectal neoplasms in our group was no greater than might be expected in the general population, subjects with two first-degree relatives tended to have more diminutive adenomas than those with one such relative. Our findings suggest that colonoscopy is not an appropriate first step in screening persons with one affected first-degree relative. For those with more complex family histories, more data are needed--particularly on the prevalence of advanced neoplasms--to determine whether a screening technique that is less costly and less invasive than colonoscopy may be adequate.

Familial risk of cancer among randomly selected cancer probands

Several investigators have reported that relatives of lung cancer probands have a greater-than-normal likelihood for developing some form of cancer. To evaluate whether this familial risk is general for probands with cancer at any site or limited to lung cancer probands, we did a case-control study in which probands having cancer affecting any body site were identified and their pedigree data were tabulated. Telephone interviews and a mailed questionnaire were used to obtain cancer histories and environmental exposures on the families of 41 lung cancer probands, 105 probands with cancer other than lung, and 127 spouse families. Cumulative tobacco exposure (P less than .05), occupational hazards (P less than .005), and age of the family relatives (P less than .0001) were found to be statistically significant predictors of cancer risk. With consideration given for these variables, we determined that siblings of lung cancer probands were at slightly greater risk of cancer of any kind (odds ratio [OR] = 1.43, P = .06) than siblings in the control group. Much of the elevated risk was attributable to an excess of lung cancer (OR = 2.49, P = .06). Siblings of non-lung/non-breast cancer probands were also determined to be at increased risk of lung cancer as well (OR = 1.61, P = .06). For parents, the risk was lower, although parental information may have been underreported.

Family history of colorectal cancer as a marker of potential malignancy within a screening program

Epidemiologic studies have shown that asymptomatic adult relatives of colorectal cancer patients are at increased risk for developing this tumor. A prospective, published pilot study confirmed this added risk and demonstrated the importance of the family history of cancer as a marker of potential malignancy. The study group was enlarged to include 471 asymptomatic adult, first degree relatives of patients having large bowel neoplasia (cancer or adenomatous polyps) but without polyposis syndromes. These first degree relatives were screened by fecal occult blood examinations and flexible sigmoidoscopy, followed by colonoscopy when indicated. Adenomatous polyps or cancer were found in 8.1% of the study group as compared with 3.7% in a comparison group of screens, not having the same family history of neoplasia and undergoing similar screening tests. Of the study group the age-adjusted rate for colorectal adenomas or cancer increased threefold (P less than 0.001) for subjects older than 40 years and an even higher fivefold relative risk was found for large bowel cancer only (P = 0.01). This was true even if there was only one relative with colorectal neoplasia (P less than 0.01) but was even more pronounced among those having more than one affected relative. The results confirm the usefulness of the family history, of even one member with large bowel neoplasia, in isolating a group at high risk for these lesions. This group would most likely benefit from regular cancer and adenomatous polyp screening particularly when older than 40 years.

Familial breast cancer in males. A case report and review of the literature

The occurrence of breast cancer in two related males, an uncle and nephew is reported. A review of previously reported cases of male breast cancer occurring in families and the association with other cancers in other family members is included. In previous reports on breast cancer in males, familial or hereditary factors have not generally been recognized as a major contributing factor. Of ten families reported (including our own) where there is sufficient information given, six families (60%) had females with breast cancer. It appears there are some families in which males as well as females have an increased risk of developing breast cancer.

Colorectal tumor screening in women with a past history of breast, uterine, or ovarian malignancies

Epidemiologic studies have shown that women who have successfully recovered from breast, uterine, or ovarian cancer have about twice the expected risk of developing colorectal cancer. These high-risk women were entered, therefore, into a large bowel screening program based on fecal occult blood detection, flexible sigmoidoscopy, and colonoscopy, when appropriate. The study group consisted of 183 women and the results were compared with 252 comparison subjects of similar age and ethnic origin. Neoplastic lesions, adenomatous polyps, or cancer were 2.5 times more frequent in the study group. However, for the largest group, women with a past history of breast cancer, the relative risk, adjusted for a family history of gastrointestinal cancer, was 3.0 (P = 0.03). This pilot study confirms the value of continuing to screen these patients, especially those with a positive family history of gastrointestinal malignancies. However, for psychological and administrative reasons, it may be better that their colon screening be integrated into a combined colon, breast, and gynecologic tumor follow-up, and not be part of a separate service.

Genetic epidemiology of familial aggregation of cancer

Literature pertaining to genetic epidemiological studies of familial cancer has been reviewed from a historical perspective. Although interest in the question of heritability of cancer was extant at least as early as the beginning of the nineteenth century, early investigators were unable to produce consistent and meaningful evidence pertaining to the issue because of unsystematic methods of data collection and inadequate methods of data analysis. During the early twentieth century, developments in the fields of genetics, statistics, and epidemiology provided concepts and methods that permitted investigators to recognize important deficiencies in past studies, and to design others in which the critical comparisons could be made between patient groups and control groups. Registries of cancer incidence in large populations became available in several countries in the middle twentieth century, providing a standard "control group" for comparison. Large surveys of site-specific cancer experience in families, rigorously designed and analyzed, found for most kinds of cancers a two- to threefold increased risk for close relatives of propositi. These studies also reemphasized the great difficulty in obtaining even minimally complete family health history information, and the importance of verifying all reported cases with medical or vital records. Although clinical and laboratory investigation will be necessary to understand the mechanisms by which human genes may predispose to cancer, epidemiological approaches can estimate the extent to which genetic etiological factors may be present in a population, whether a general population or one defined by other factors under investigation. Population-based studies are already of practical significance to the clinical geneticist in the estimation of risk of eventual cancer development in unaffected family members, and can be expected to continue to identify specific groups and characteristics associated with genetic cancer predisposition. Finally, segregation and linkage analysis and their present applications to family studies of cancer were reviewed. As a result of the increasing number of DNA polymorphisms that are becoming available due to developments in molecular biology, the human gene map can be expected to be well defined in the near future, and investigation of families using segregation and linkage analysis will then be instrumental in defining the role of heredity in the development of cancer in human populations.

Multiple myeloma and family history of cancer. A case-control study

A hospital-based case-control study was done to examine the hypothesis that persons with a family history of multiple myeloma (MM) or other cancers are at increased risk of multiple myeloma. Study members were 439 cases of multiple myeloma and 1317 matched controls seen at the Duke University Medical Center. Only 3 cases and 4 controls reported multiple myeloma in their families. The relative risk (RR) was 2.3, but the 95% confidence interval (CI) was 0.5-10.1, allowing no firm conclusion about the risk associated with familial MM. A family history of cancer of any type resulted in a relative risk of MM of 1.4 (CI: 1.1-1.8). This association was strongest (RR = 2.5, CI: 1.1-5.3) among young study members (age less than or equal to 49). A family history of hematologic malignancy (ICD 200-208) resulted in a RR of 2.4 (95% CI: 1.4-4.0). The data also suggested that a family history of lung cancer, breast cancer, and genitourinary cancer may be associated with increased risk of myeloma in older persons.

Ovarian cancer. Geographical, host and environmental factors. An overview

The incidence of ovarian cancer is reviewed among different races and ethnic groups. We present the effect of socio-economic class, age, endocrinological factors, menstrual cycle, reproductive history, familial, and genetic factors, viral infections, chemical carcinogens, and previous exposure to radiation on the incidence of ovarian cancer. There is evidence that environmental factor affects the distribution of various types of ovarian cancer. Migration may also change the susceptibility to this disease and the mean age was varied between countries being lowest where incidence was highest. The disease appeared to have a familial incidence. The protective effect of oral contraceptive steroids and the role of asbestos as a chemical carcinogen are discussed.

Familial breast cancer in Iceland

Women who have relatives known to have had breast cancer are at an increased risk of getting the disease compared with the general population. On the basis of an extensive collection of family trees of women with breast cancer, the magnitude of this increase in risk is computed. Previously published results on other breast cancer risk factors are drawn upon and it has been possible to take account of some of these e.g., age, decade of birth, age at first childbirth and parity in the risk estimates. The relative risk with such adjustment is found to be 2.59 for mothers and 2.56 for sisters.

Problems in the assessment of relative risk of chronic disease among biological relatives of affected individuals

A question often asked in regard to a chronic disease is whether the risk to a biological relative of a case is evaluated, and if so by how much the risk is altered. To answer this question, data may be collected directly with genetic objectives in mind by ascertaining population of pedigrees. More often, the initial assessment of the question comes from family history data collected in an incidental manner in the course of a case-control or similar type of study. This paper discusses some limitations to the inferences which can be derived from such casual family history data. These include (i) poor statistical properties of standard relative risk measures, (ii) interpretational problems of observed relative risks when affected cases arise from genetic as well as nongenetic causes and when genes may not always be expressed in individuals in whom they are present, and (iii) confounding effects which may occur when a high risk allele alters the age of onset pattern of the disease. These problems result largely from a loss of design control over the degree of exposure of individuals ascertained and can lead to a small observed relative risk value even when genetic factors are important. Suggestions for handling such casual family history data are offered.

Selective screening for colorectal tumors in the Tel-Aviv area: relevance of epidemiology and family history

A selective screening program for the early detection of colorectal tumors was carried out in the Tel-Aviv area. The criteria for inclusion were based, in part, on relevant epidemiologic data which showed that European- and American-born immigrants were at the highest risk for developing this cancer, followed by Israel-born Jews. The Tel-Aviv area, because of its large elderly population of European origin, has a high incidence of colorectal cancer. Families of patients with colon cancer are known to have an increased risk for developing colon tumors. These relatives were actively searched for, and were, along with the control group, examined by Hemoccult testing and flexible sigmoidoscopy. The color tumor (cancer or adenomatous polyps) rate was 6.3% in the group with a family history of colon cancer, as contrasted to 3.8% in a smaller control group without this history. This increased yield, greater than usually found in an unselected population, emphasizes the economic value of selective screening utilizing relevant epidemiologic data and the family history.