Benign breast biopsy diagnosis and subsequent risk of breast cancer.

BACKGROUND: We examine benign breast biopsy diagnoses as reported by community pathologists in New Mexico and investigate associations with future breast cancer development. METHODS: Using data collected between 1992 and 2000 by the New Mexico Mammography Project and cancer data through 2003 from the New Mexico Tumor Registry, we calculated breast cancer rates following 14,602 benign breast biopsies for women ages 30 to 89 years. For comparison, we also calculated the breast cancer rate following 215,283 normal screening mammograms. Hazard ratios (HR) are presented. RESULTS: We identified 480 subsequent breast cancer diagnoses among 14,602 women with benign breast biopsies and 4,402 breast cancer diagnoses among 215,283 women with mammograms assigned a "negative" or "benign finding" assessment. Histologic diagnoses in absence of atypia had an age-adjusted HR of 1.95 [95% confidence interval (95% CI), 1.77-2.15]. Among low-risk histologic diagnoses, the strongest associations with subsequent breast cancer development included adenosis, apocrine metaplasia, calcifications, and ductal hyperplasia. Fibroadenoma, inflammation, and cysts did not exhibit an association with breast cancer development. Women with low-risk diagnoses and breast tissue characterized as fatty or with scattered densities had a HR of 2.09 (95% CI, 1.68-2.60), whereas women with low-risk histologic diagnoses and dense breasts had a HR of 3.36 (95% CI, 2.83-3.99). CONCLUSIONS: The observed breast cancer occurrence contributes to evidence of increased risk following benign biopsy. The risk associated with histologic diagnoses in absence of atypia was twice the risk experienced by women with normal mammogram evaluations and may be modified by breast density.

Information on chemotherapy and hormone therapy from tumor registry had moderate agreement with chart reviews.

BACKGROUND: Surveillance, Epidemiology, and End Results (SEER) cancer registries provide accurate information on cancer surgery and radiation, but the validity of registry data on chemotherapy and hormone therapy for breast cancer has not been well studied. We validated the registry data for chemotherapy and hormone therapy against an independent medical chart review. METHODS: We identified 1,228 women diagnosed with breast cancer at age > or = 65 in 1993-1999 in the New Mexico SEER Tumor Registry and completed medical chart reviews. RESULTS: Overall, there was moderate agreement between these two databases on chemotherapy that was received within 6 months of diagnosis. The observed agreement was 96.0%, with a kappa of 0.72 (95% confidence interval: 0.64-0.79). The sensitivity of the registry data for chemotherapy was 70.7% and the specificity was 98.2%. The positive predictive value of the registry data for chemotherapy was 77.8%. The sensitivity of the registry data for hormone therapy was 59.7%, and the specificity was 89.5%. The observed agreement for hormone therapy was 80.0%, with a kappa of 0.52 (0.46-0.57). CONCLUSION: Agreement on chemotherapy and hormone therapy between the New Mexico SEER Tumor Registry and chart reviews was moderate. The preferred approach would be to combine data from different sources to obtain more complete information.

Tissues from population-based cancer registries: a novel approach to increasing research potential.

Population-based cancer registries, such as those included in the Surveillance, Epidemiology, and End-Results (SEER) Program, offer tremendous research potential beyond traditional surveillance activities. We describe the expansion of SEER registries to gather formalin-fixed, paraffin-embedded tissue from cancer patients on a population basis. Population-based tissue banks have the advantage of providing an unbiased sampling frame for evaluating the public health impact of genes or protein targets that may be used for therapeutic or diagnostic purposes in defined communities. Such repositories provide a unique resource for testing new molecular classification schemes for cancer, validating new biologic markers of malignancy, prognosis and progression, assessing therapeutic targets, and measuring allele frequencies of cancer-associated genetic polymorphisms or germline mutations in representative samples. The assembly of tissue microarrays will allow for the use of rapid, large-scale protein-expression profiling of tumor samples while limiting depletion of this valuable resource. Access to biologic specimens through SEER registries will provide researchers with demographic, clinical, and risk factor information on cancer patients with assured data quality and completeness. Clinical outcome data, such as disease-free survival, can be correlated with previously validated prognostic markers. Furthermore, the anonymity of the study subject can be protected through rigorous standards of confidentiality. SEER-based tissue resources represent a step forward in true, population-based tissue repositories of tumors from US patients and may serve as a foundation for molecular epidemiology studies of cancer in this country.

Discrepancy between consensus recommendations and actual community use of adjuvant chemotherapy in women with breast cancer.

BACKGROUND: Although the efficacy of adjuvant chemotherapy in prolonging survival for women with breast cancer has been well documented, limited population-based information is available on the actual use of chemotherapy. OBJECTIVE: To examine the relationship between age and chemotherapy use. DESIGN: Cohort study. SETTING: New Mexico. PATIENTS: 5101 women 20 years of age or older receiving a diagnosis of stage I, stage II, or stage IIIA breast cancer from 1991 through 1997. MEASUREMENTS: Pattern of chemotherapy use by age; logistic regression analysis to generate the odds and probabilities of receiving chemotherapy; and sensitivity analysis to estimate potential effects of unmeasured confounders. RESULTS: Overall, 29% of women received chemotherapy. The rate of chemotherapy use for women with stage I, stage II, or stage IIIA breast cancer was 11%, 47%, and 68%, respectively. Across all tumor stages, the use of chemotherapy decreased substantially with increasing age (P < 0.001). Overall, 66% of women younger than 45 years of age received chemotherapy compared with 44% of women between 50 and 54 years of age, 31% of women between 55 and 59 years of age, and 18% of women between 60 and 64 years of age. The decreasing pattern of chemotherapy use with age continued after adjustment for prognostic factors and was relatively insensitive to changes in unmeasured factors. CONCLUSIONS: There is considerable discrepancy between the 1990 National Institutes of Health Consensus Conference recommendations for chemotherapy administration in women with breast cancer and the actual use of chemotherapy in the community. The decrease in use with age may relate to the decreasing efficacy of chemotherapy with age, as reported in clinical trials. Outcomes studies should address whether the recommendations are overly aggressive or whether practicing oncologists are too conservative in their use of chemotherapy.

Changes in nonmelanoma skin cancer incidence between 1977-1978 and 1998-1999 in Northcentral New Mexico.

Nonmelanoma skin cancer (NMSC) is a highly common form of malignant disease in light-skinned populations. In 1977-1978, the National Cancer Institute sponsored a population-based skin cancer survey that found marked geographic variability in the incidence of NMSC within the United States. Some of the highest rates were observed in the southwestern state of New Mexico within its non-Hispanic white population. We recently undertook a follow-up survey of NMSC in New Mexico and report here incidence rate data for non-Hispanic white residents of a three-county area in northcentral New Mexico for two 12-month time periods: June 1, 1977 to May 31, 1978 and July 1, 1998 to June 31, 1999. Our results show that incidence rates of basal cell carcinoma increased by 50% in males and 20% in females, whereas rates of squamous cell carcinoma roughly doubled in both males and females. Temporal analysis of rates according to major anatomical site showed the head and neck was consistently the most frequent site of occurrence, however, the greatest percentage increase in rates over time occurred at the upper and lower limbs. These findings are consistent with those reported for various other populations showing the incidence of NMSC has measurably increased since the 1970s.

Effects of misattribution in assigning cause of death on prostate cancer mortality rates.

PURPOSE: Estimate the magnitude of misattribution in death certification and to determine whether misattribution could explain temporal trends in New Mexico prostate cancer mortality. METHODS: Investigators retrospectively reviewed medical records to classify cause of death for men with prostate cancer who died in New Mexico in either 1985 or 1995. The investigator-assigned cause of death, either prostate cancer or another cause, was compared with the New Mexico Bureau of Vital Statistics' (BVS) assignment. Net misattribution was the difference between BVS and investigators in the number of deaths attributed to prostate cancer relative to the number attributed by investigators. RESULTS: Concordance for death certification between BVS and investigators was higher in 1995 (95.8%) than 1985 (85.1%), p <0.01, but net misattribution was higher in 1995 (16.8% vs. 1.9%). During this time, the crude prostate cancer mortality rate in New Mexico increased 33.5%, from 18.5 to 24.7 per 100,000. However, after adjusting for misattribution, mortality increased only 15.9%, from 18.2 to 21.1 per 100,000. CONCLUSIONS: Net misattribution in death certification was higher in 1995 than 1985. The adjusted increase in crude mortality rates was substantially less than the observed increase, suggesting that misattribution explained about half of the observed increase.

Trends in gestational choriocarcinoma: a 27-year perspective.

OBJECTIVE: To evaluate trends in incidence and survival rates for gestational choriocarcinoma with the use of population-based data. METHODS: Overall and 5-year average age-adjusted incidence rates were computed with the Surveillance, Epidemiology, and End Results program public-use database. Differences by age at diagnosis, race, stage, registry, and over calendar time were compared by Poisson regression, and survival censored for deaths other than choriocarcinoma by log-rank tests and Cox's proportional hazard ratios. RESULTS: Between 1973 and 1999, 450 cases were recorded. The annualized age-adjusted incidence rate for choriocarcinoma was 0.133 per 100,000 woman-years and decreased by 49.7% (2.8% per year). By race (whites, blacks, and others), incidence rates declined by 62.3%, 27.2%, and 54.3%, respectively. In the Poisson model evaluating incidence rates, age, race, registry, and stage were significant main effects. Compared with whites, the relative risk was higher for blacks (2.14, 95% confidence interval [CI] 1.60, 2.86) and others (2.30, 95% CI 1.67, 3.18). Rates were highest in Utah and lowest in Iowa. By age at diagnosis, rates were higher in 20-39-year-olds. The 5-year relative survival rate was 89.5%. Censored survival was significantly lower among blacks (whites 92.4%, blacks 84.9%, others 87.1%, P = .045), for advanced disease (localized 94.5%, regional 92.9%, distant 87.1%, P = .02), and with increasing age at diagnosis (P = .017). Age and calendar time significantly influenced censored survival independent of stage and registry. CONCLUSION: Gestational choriocarcinoma incidence rates have declined and survivals have improved, but blacks continue to have higher incidence and lower survival rates.

Prostate-specific antigen testing accuracy in community practice.

BACKGROUND: Most data on prostate-specific antigen (PSA) testing come from urologic cohorts comprised of volunteers for screening programs. We evaluated the diagnostic accuracy of PSA testing for detecting prostate cancer in community practice. METHODS: PSA testing results were compared with a reference standard of prostate biopsy. Subjects were 2,620 men 40 years and older undergoing (PSA) testing and biopsy from 1/1/95 through 12/31/98 in the Albuquerque, New Mexico metropolitan area. Diagnostic measures included the area under the receiver-operating characteristic curve, sensitivity, specificity, and likelihood ratios. RESULTS: Cancer was detected in 930 subjects (35%). The area under the ROC curve was 0.67 and the PSA cutpoint of 4 ng/ml had a sensitivity of 86% and a specificity of 33%. The likelihood ratio for a positive test (LR+) was 1.28 and 0.42 for a negative test (LR-). PSA testing was most sensitive (90%) but least specific (27%) in older men. Age-specific reference ranges improved specificity in older men (49%) but decreased sensitivity (70%), with an LR+ of 1.38. Lowering the PSA cutpoint to 2 ng/ml resulted in a sensitivity of 95%, a specificity of 20%, and an LR+ of 1.19. CONCLUSIONS: PSA testing had fair discriminating power for detecting prostate cancer in community practice. The PSA cutpoint of 4 ng/ml was sensitive but relatively non-specific and associated likelihood ratios only moderately revised probabilities for cancer. Using age-specific reference ranges and a PSA cutpoint below 4 ng/ml improved test specificity and sensitivity, respectively, but did not improve the overall accuracy of PSA testing.

Gestational trophoblastic neoplasia in American Indians.

OBJECTIVE: To analyze gestational trophoblastic neoplasia (GTN) trends among American Indians (AI) using population-based data. STUDY DESIGN: GTN incidence, by race and age, was calculated using data collected by the New Mexico Tumor Registry over 29 years (1973-2001). Live birth, pregnancy and women at risk were tabulated using data derived from the state's vital record annual reports and from the registry. Statistical methods included trends analysis and Poisson regression. There is no national registry in the United States for all GTN. Therefore, the Surveillance, Epidemiology and End Results (SEER) database was used to identify choriocarcinoma cases in American Indians between 1973 and 1999. RESULTS: Within New Mexico, 1,082 cases of GTN were identified among 752,374 live births and 904,831 pregnancies, with ratios of 1:695 and 1:836, respectively, affecting 234 AI, 355 non-Hispanic whites (NHW), 463 Hispanic whites (HW) and 30 other nonwhites. Ratios per live births (pregnancy), respectively, were significantly higher in AI (AI 1:439 [1:487], NHW 1:739 [1:949], HW 1:783 [1:903]), as was age-adjusted incidence per 100,000 woman-years (AI 10.62, NHW 3.53, HW 5.15; all P<.0001). Using Poisson models with live birth and woman-year denominators, AI were found to be at increased risk for all GTN histologic subsets (complete, partial and invasive hydatidiform mole and choriocarcinoma). Of 524 total gestational choriocarcinoma cases identified within SEER, 8 (1.8%) affected American Indians; of them, 7 were from New Mexico. CONCLUSION: In New Mexico, AI continue to be at higher risk of GTN than are other groups. Given the rarity of choriocarcinoma within SEER, especially among AI, the New Mexico dataset provides the best available estimate of trends in U.S. AI GTN risk.

Human papillomavirus genotype distributions: implications for vaccination and cancer screening in the United States.

BACKGROUND: Limited data are available describing human papillomavirus (HPV) genotype distributions in cervical cancer in the United States. Such studies are needed to predict how HPV vaccination and HPV-based screening will influence cervical cancer prevention. METHODS: We used the New Mexico Surveillance, Epidemiology, and End Results Registry to ascertain cases of in situ (n = 1213) and invasive (n = 808) cervical cancer diagnosed during 1985-1999 and 1980-1999, respectively, in the state of New Mexico. HPV genotyping was performed using two polymerase chain reaction-based methods on paraffin-embedded tissues from in situ and invasive cancers and on cervical Papanicolaou test specimen from control subjects (ie, women aged 18-40 years attending clinics for routine cervical screening [n = 4007]). Relative risks for cervical cancer were estimated, and factors associated with age at cancer diagnosis and the prevalence of HPV genotypes in cancers were examined. RESULTS: The most common HPV genotypes detected in invasive cancers were HPV type 16 (HPV16, 53.2%), HPV18 (13.1%), and HPV45 (6.1%) and those in in situ cancers were HPV16 (56.3%), HPV31 (12.6%), and HPV33 (8.0%). Invasive cancer case subjects who were positive for HPV16 or 18 were diagnosed at younger ages than those who were positive for other carcinogenic HPV genotypes (mean age at diagnosis: 48.1 [95% confidence interval {CI} = 46.6 to 49.6 years], 45.9 [95% CI = 42.9 to 49.0 years], and 52.3 years [95% CI = 50.0 to 54.6 years], respectively). The proportion of HPV16-positive in situ and invasive cancers, but not of HPV18-positive cancers, declined with more recent calendar year of diagnosis, whereas the proportion positive for carcinogenic HPV genotypes other than HPV18 increased. CONCLUSIONS: HPV16 and 18 caused the majority of invasive cervical cancer in this population sample of US women, but the proportion attributable to HPV16 declined over the last 20 years. The age at diagnosis of HPV16- and HPV18-related cancers was 5 years earlier than that of cancers caused by carcinogenic HPV genotypes other than HPV16 and 18, suggesting that the age at initiation of cervical screening could be delayed in HPV-vaccinated populations.

External validation of medicare claims for breast cancer chemotherapy compared with medical chart reviews.

BACKGROUND: Although Medicare claims data have been increasingly used to examine the patterns and outcomes of cancer chemotherapy, their external validity has not been well studied. OBJECTIVES: We sought to validate Medicare claims for chemotherapy compared with medical chart reviews. PATIENTS AND METHODS: We completed medical chart reviews for 1228 women who were diagnosed with breast cancer at age 65 and older between 1993 and 1999 in New Mexico that were linked with Medicare claims data, achieving an estimated sensitivity of more than 90% and a 0.05 level of precision. RESULTS: Of the 150 subjects identified by Medicare claims as receiving chemotherapy within 6 months of diagnosis, 75% were confirmed by medical records as having received chemotherapy. Of the remaining 25% of cases without chart verification, (1) 33 cases had 7 or more claims for chemotherapy and also had specific chemotherapy drugs indicated in Medicare data, representing 22% (33/150) of all cases that received chemotherapy according to Medicare claims and (2) 4 cases had 1 to 6 claims for chemotherapy, representing 3% (4/150) of all cases with claims for chemotherapy. Of those 1078 subjects who did not receive chemotherapy according to Medicare claims, more than 99% were confirmed by chart reviews. Observed agreement on chemotherapy between Medicare claims and chart reviews was 94% and overall reliability (kappa) was 0.69 (95% confidence interval = 0.63-0.76). CONCLUSIONS: Of cases identified as receiving chemotherapy by Medicare claims, 97% had strong evidence and only 3% had weak evidence for receiving this therapy.

Pathologic findings from the Breast Cancer Surveillance Consortium: population-based outcomes in women undergoing biopsy after screening mammography.

BACKGROUND: To the authors' knowledge, a comprehensive analysis of pathology outcomes after screening mammography, as it is practiced clinically in the U.S. general population, has not been performed. METHODS: Breast Cancer Surveillance Consortium data from 1996-2001 were used to identify pathology specimens that were obtained within 1 year of screening mammograms performed on 786,846 women ages 40-89 years. The pathology results were classified as invasive carcinoma, ductal carcinoma in situ (DCIS), or benign. The associations between overall pathology outcomes and invasive tumor size and lymph node status were analyzed by age and mammography assessment category. RESULTS: The rates of both recommending and performing a biopsy varied little with age. The 1,664,032 screening mammograms were followed by 26,748 known biopsies (1.6%) and 8815 diagnoses of breast carcinoma (0.53%). Overall, 81% of carcinomas were invasive, and 78% of those were pathologically lymph node-negative tumors, in contrast to the 66% prevalence observed in the Surveillance, Epidemiology, and End Results (SEER) data during the same period. Most invasive tumors measured between 0 mm and 10 mm (35%) or between 11 mm and 20 mm (36%) in greatest dimension, and 92% and 78% were lymph node-negative tumors, respectively: Biopsy results that were classified as malignant increased with age (P < 0.0001) and were most likely to follow Breast Imaging, Reporting, and Diagnosis System Category 5 and 4 assessments, respectively. Ductal hyperplasia (19.6%), fibroadenoma (18.5%), and other benign findings (56.1%) were the most common benign diagnoses. CONCLUSIONS: Pathologically negative lymph nodes were more prevalent in this mammographically screened population than in the overall SEER population. The prevalence of invasive carcinoma, DCIS, and benign findings presented herein establish a range of expected biopsy outcomes for women after screening mammography in the general U.S. population.

The frequency of ipsilateral second tumors after breast-conserving surgery for DCIS: a population based analysis.

BACKGROUND: The diagnosis of ductal carcinoma in situ (DCIS) is increasing, although to the authors' knowledge there is no consensus regarding optimal treatment. This analysis of women treated with breast-conserving surgery (BCS) evaluated the impact of radiation therapy (RT) in patient outcomes. METHODS: The current study included a population-based sample of 1103 women residing in selected Surveillance, Epidemiology, and End Results (SEER) registries who were diagnosed with DCIS between 1991-1992. Data were obtained from the registry, physician follow-up, and pathology reports. Physicians were contacted in 1999 to determine whether the patient had developed a second event in the ipsilateral breast. For second events, pathology reports were reviewed to determine the presence of in situ or invasive disease. Registry data through 2001 were used to assess death rates and cause of death. Cox proportional hazards and logistic regression models were used to evaluate the rates of second events and breast carcinoma deaths between women treated with and without RT. RESULTS: Over an average of 91 months, 13.2% of women developed a second event. Rates of second events were 11% for women treated with BCS and RT compared with 15% for women treated with BCS only (adjusted hazards ratio, 0.64; 95% confidence interval, 0.44-0.92). Women receiving RT were significantly less likely to develop invasive breast carcinoma in the ipsilateral breast (adjusted odds ratio, 0.40). By 2001, the rate of death from breast carcinoma was 2.7%; in the group of women treated with BCS only compared with 0.8% in the group of women treated with BCS with RT. CONCLUSIONS: Among a population-based cohort, RT was found to significantly reduce the risk of second events in the ipsilateral breast, particularly invasive tumors, although not to the extent reported in clinical trials.

Community-based assessment of adjuvant hormone therapy in women with breast cancer, 1991-1997.

This study used population-based tumor registry data to describe the patterns of adjuvant hormone therapy and to examine the correlates of hormone therapy for women with breast cancer. The study population included 5101 women (age 20 years) who were diagnosed with breast cancer in 1991 through 1997 in the entire state of New Mexico. Overall, 32% of women with stage I, II, or IIIA breast cancer received adjuvant hormone therapy. The likelihood of receiving adjuvant hormone therapy increased with tumor stage at diagnosis. Women less than 50 years of age were significantly less likely to receive adjuvant hormone therapy compared to those age 50 to 54 years, but there was no significant difference in the use of adjuvant hormone therapy for women age 55 years and older. The use of adjuvant hormone therapy was influenced by hormone receptor status and lymph node status. Patients who received adjuvant chemotherapy were also more likely to receive adjuvant hormone therapy than those who did not. The use of adjuvant hormone therapy alone was relatively stable over time and the use of adjuvant chemotherapy alone increased, but the receipt of chemotherapy combined with hormone therapy decreased from 1991 to 1997. There was no significant difference with age in the use of adjuvant hormone therapy among 55-year-old women compared to those age 50 to 54 years, whereas women less than 50 years of age were significantly less likely to receive this therapy. The use of adjuvant hormone therapy varied significantly by tumor stage, lymph node status, hormone receptor status, and the receipt of adjuvant chemotherapy.

Is there a difference in survival for IA1 and IA2 adenocarcinoma of the uterine cervix?

OBJECTIVE: The goal of this study was to determine if International Federation of Obstetrics and Gynecology (FIGO) subdivision into IA1 versus IA2 is predictive of survival differences for early invasive adenocarcinoma. METHODS: The Surveillance, Epidemiology, and End-Results (SEER) Public-Use Database was used to identify all cases of IA1 and IA2 adenocarcinoma diagnosed between 1983 and 1997. A systematic literature search (MEDLINE 1966-2000) was used to identify all previously published cases. Stage, depth of invasion, node status, therapy, and survival were analyzed using Fisher's exact and log-rank tests. RESULTS: In SEER, 560 cases were identified: 200 IA1, 286 IA2, and 74 localized. Simple hysterectomy was performed in 272 (48.6%) and radical hysterectomy in 210 (37.5%). Positive lymph nodes were found in 3 of 197 (1.5%) who underwent lymphadenectomy, 2 of whom died. The censored survival by stage (mean follow-up 51.6 months) was not significantly different (P = 0.77) for IA1 versus IA2 (98.5% vs 98.6%). Combining these data with all other published series of early cervical adenocarcinoma, 1170 cases were identified, including 585 IA1, 358 IA2, and 227 "others," with less defined early disease. Of 531 (45.4%) who underwent lymphadenectomy, 15 (1.28%) had one or more positive nodes; of these, 11 (73.3%) recurred or died. For IA1 versus IA2 disease, there were no significant differences in the frequency of positive lymph nodes, recurrence, or death. However, "others," those with less well-defined lesions, or larger than IA2, were at increased risk. CONCLUSION: Early invasive adenocarcinoma (IA1 and IA2) has an excellent prognosis and conservative surgery may be appropriate. Since current FIGO staging definitions do not distinguish high- from low-risk disease, individualization of therapy based on pathology review, risk assessment, and patient preference is recommended.

Ethnic differences at risk for gestational trophoblastic disease in New Mexico: A 25-year population-based study.

OBJECTIVE: The purpose of this study was to compare gestational trophoblastic disease incidence rates with the use of population-based data. STUDY DESIGN: All incident cases between 1973 and 1997 and live birth, pregnancy, and women at risk were tabulated with the use of data that were derived from the New Mexico Tumor Registry and Vital Records and Health Statistics Annual Reports. Statistical methods included trends analyses, odds ratios, and Poisson regression. RESULTS: Of 939 total cases, 312 non-Hispanic white women, 399 Hispanic white women, 201 American Indian women, and 27 other women were affected. Age-adjusted incidence rates were significantly higher for American Indian women (11.16%) compared with non-Hispanic (3.57%) or Hispanic white women (5.32%); the probability value was <.001. When live birth (1:438 women) and pregnancy (1:486 women) denominators were considered, American Indian women alone were at increased risk, and the ratio increased by 56% over 25 years. American Indian women were also at increased risk for partial mole (relative risk, 4.03; 95% CI, 2.57-6.31), invasive mole (relative risk, 26.7; 95% CI, 7.81-93.14), and choriocarcinoma (relative risk, 6.29; 95% CI, 1.81-22.66) variants. CONCLUSION: American Indians are at increased risk relative to the other predominant ethnic groups in New Mexico. Age-adjusted standardization provided a reproducible measurement that may be applicable across other registries.