A prospective study of serum soluble CD30 concentration and risk of non-Hodgkin lymphoma

CD30 is a member of the tumor necrosis factor receptor superfamily. Originally described as a marker on Reed-Sternberg cells in Hodgkin lymphoma (HL), CD30 is expressed widely in HL and anaplastic large-cell lymphoma (ALCL), a rare subtype of non-Hodgkin lymphoma (NHL), and infrequently expressed among other types of NHL.^1,2  Among normal lymphocytes, CD30 is expressed only by activated B cells and T cells. In the case of T cells, CD30 is preferentially expressed by activated cells predisposed to producing T helper 2 (Th2)–type B-cell–stimulatory cytokines.^3,4  The interaction of CD30 with its ligand (CD30L) appears to promote secondary humoral responses in normal B cells.⁵  The effects of CD30 activation on tumor cells appear to be complex: they appear to induce cell proliferation in HL cells of T-cell origin and to promote apoptosis in ALCL cells.^6,7 

The extracellular portion of CD30 is proteolytically cleaved from CD30⁺ cells, possibly on activation by CD30L, to produce a soluble form of the molecule (sCD30) detectable in serum.⁵  Elevated serum sCD30 is observed for several viral infections, autoimmune diseases, and atopic conditions,^1,5  and has been proposed as a marker for a Th2-oriented immune response.^4,8,9  Increased circulating sCD30 is also present among CD30⁺ lymphoid malignancies such as HL and ALCL.^1,5  The physiologic effects, if any, of sCD30 are unknown.^5,6 

Sustained B-cell proliferation is suspected to be an important mechanism contributing to the accumulation of genetic errors that can lead to lymphomagenesis.^10,11  Breen et al recently hypothesized that elevated circulating sCD30 levels reflect an immunologic milieu conducive to B-cell NHL,¹²  which includes more than 90% of all diagnosed NHL.¹³  In a small nested case-control investigation conducted within the Multicenter AIDS Cohort Study, they observed significantly higher baseline serum sCD30 levels among persons who subsequently developed AIDS-related NHL compared with cancer-free controls.¹² 

To determine whether circulating sCD30 levels are associated with NHL risk among immunocompetent persons, we conducted a nested case-control study within the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial.

Detailed descriptions of the PLCO Cancer Screening Trial have been previously reported. In brief, between 1993 and 2001, approximately 155000 subjects in 10 cities (Birmingham, AL; Denver, CO; Detroit, MI; Honolulu, HI; Marshfield, WI; Minneapolis, MN; Pittsburgh, PA; Salt Lake City, UT; St Louis, MO; and Washington, DC) 55 to 74 years of age were recruited from the general population and randomized to the screening or nonscreening arm of the study. All screening-arm subjects provided nonfasting baseline blood samples that were processed and frozen within 2 hours of collection and stored at −70°C. Persons were followed up for all cancer diagnoses by annual mailed questionnaire, in addition to the PLCO Cancer Screening Trial disease outcomes by annual screening examinations during the first 6 years of follow-up. All cancer diagnoses were pathologically confirmed by medical record abstraction. The institutional review boards of the National Cancer Institute and the 10 study centers approved the trial, and all participants provided written informed consent in accordance with the Declaration of Helsinki.

After follow-up through January 31, 2006, 297 cases of NHL (ICD-O-2-M 9590-9595, 9670-9677, 9680-9688, 9690-9698, 9700-9717, 9823, 9827) were identified from 54829 eligible screening-arm participants (eligibility criteria: signed informed consent, no history of cancer at enrollment, 2 or more unthawed serum vials available, did not develop cancer or exit the cohort within the first year of follow-up). Controls were individually matched to cases (1:1 ratio) by age at baseline (5-year categories), sex, race, PLCO center, and date of baseline blood draw (3-month categories) from among subjects who had not been diagnosed with any type of malignancy except nonmelanoma skin cancer at the time of the case diagnosis date.

Serum sCD30 was measured in duplicate by enzyme-linked immunosorbent assay (Bender Medsystems). Cases and their matched controls were assayed consecutively within the same batch. Measurements from blinded quality control replicates interspersed among the samples suggested possible problems with assay variation in 4 of 17 assay batches. We present results with these batches excluded (resulting sample size: 234 cases, 234 controls; assay coefficient of variation, 38%; intraclass correlation, 0.66), although our findings for the total dataset of 297 cases and 297 controls were virtually identical (supplemental Table 1, available on the Blood website; see the Supplemental Materials link at the top of the online article).

The Wilcoxon signed-rank test was used to test for significant differences in sCD30 levels among the matched pairs of cases and controls. Odds ratios (ORs) and 95% confidence intervals (CIs) relating sCD30 concentration categories and NHL risk were then computed using conditional logistic regression modeling. For analyses of all NHL, sCD30 concentration (averaged across duplicates) was categorized using control quartiles as cut-points. Tests for trend were performed by modeling the intracategory medians as a continuous parameter. We additionally investigated associations with dichotomized sCD30 concentration (cut-point: control median) for NHL histologic subtypes (small lymphocytic lymphoma/chronic lymphocytic leukemia [SLL/CLL], diffuse large B-cell lymphoma [DLBCL], follicular lymphoma [FL], other or not otherwise specified histology) using polytomous regression models adjusted for baseline age, sex, race, PLCO center, and enrollment year. Analyses stratified by follow-up time (1-2, 3-5, 6-10 years) were also performed. All statistical tests were 2-sided.

The study sponsors had no role in study design, data collection, data analysis, data interpretation, writing of the report, or the decision to submit a paper for publication.

Cases and controls had identical distributions of matching factors (Table 1). Soluble CD30 concentration was 39% higher in cases compared with controls (P < .001) and remained significantly elevated among cases diagnosed 6 to 10 years after providing a blood sample (Table 2). The relative risk of NHL increased with increasing sCD30 levels, both overall (OR [95% CI] for second, third, and fourth quartiles vs first quartile: 1.4 [0.8-2.6], 2.2 [1.2-4.1], and 4.1 [2.2-7.8], respectively; P_trend < .001) and within each follow-up time stratum (Table 3). Dichotomized sCD30 was associated with increased risk for each NHL subtype, FL in particular (OR [95% CI]: SLL/CLL, 1.8 [1.1-3.0]; DLBCL, 2.0 [1.0-3.9]; FL, 5.9 [2.4-14.1]; other/not otherwise specified, 2.1 [1.0-4.3]). We note that SLL/CLL was more prevalent than DLBCL among our case series. This pattern is consistent with the older age distribution of PLCO subjects (age 55-74 at enrollment) and the age-specific incidence of these subtypes past the age of 55.¹⁴ 

Breen et al previously reported that elevated serum sCD30 is associated with an increased risk of AIDS-related NHL in a study of 49 cases and 135 controls, although their study was limited by a relatively short time period between blood collection and NHL diagnosis (< 3 years).¹²  Our study, to our knowledge the first investigation of sCD30 and NHL reported in a healthy population, also shows a clear association between sCD30 concentration and subsequent NHL risk, apparent as far as 6 to 10 years after blood collection. These findings suggest that B-cell activation is an important mechanism underlying lymphomagenesis among severely immune depressed and immunocompetent populations alike.

In conclusion, our study findings strongly suggest that elevated serum levels of sCD30 predict the development of NHL. Additional research is needed to confirm these findings and to better understand the biologic basis of this relationship.

The authors thank Drs Christine Berg and Philip Prorok, Division of Cancer Prevention, National Cancer Institute, the Screening Center investigators and staff of the PLCO Cancer Screening Trial; Mr Tom Riley and staff, Information Management Services Inc; Ms Barbara O'Brien and staff, Westat Inc; Ms Jackie King and staff, BioReliance Inc; and Ms Georgina Mbisa and Dr Rachel Bagni, Viral Technology Laboratory at SAIC-Frederick; as well as the study participants for their contributions to making this study possible.

This work was supported in whole or in part with federal funds from the National Cancer Institute, National Institutes of Health (contract HHSN261200800001E).

The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the US Government.

National Institutes of Health

Contribution: M.P.P. led the design of the study and the statistical analysis and wrote the manuscript; Q.L., D.B., and N.R. also contributed to the design and analysis of the study; the laboratory of B.C. conducted the assays; M.M.O., W.-Y.H., and W.H. contributed to the conduct of the PLCO Cancer Screening Trial; O.M.-M. advised on assay selection and provided intellectual input into the manuscript; and all authors provided intellectual input into the manuscript.

Conflict-of-interest disclosure: The authors declare no competing financial interests.

Correspondence: Mark P. Purdue, Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, EPS 8009, 6120 Executive Blvd, Bethesda, MD 20892; e-mail: purduem@mail.nih.gov.