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Originally published as JCO Early Release 10.1200/JCO.2006.09.0118 on June 4 2007 © 2007 American Society of Clinical Oncology. Plasma Testosterone and Prognosis of Postmenopausal Breast Cancer Patients
From the Department of Preventive and Predictive Medicine; Scientific Directorate; and Chemoprevention Unit, Fondazione IRCCS "Istituto Nazionale dei Tumori"; and the European Institute of Oncology, Milan, Italy Address reprint requests to Andrea Micheli, PhD, Fondazione IRCCS "Istituto Nazionale dei Tumori," Via Venezian 1, 20133 Milan, Italy; e-mail: andrea.micheli{at}istitutotumori.mi.it
Purpose: High endogenous testosterone is associated with increased breast cancer (BC) risk. We designed this study specifically to assess the long-term prognostic role of testosterone in a cohort of postmenopausal BC patients. Patients and Methods: We considered 194 postmenopausal women, operated on for early BC (T1-2N0M0), who never received chemotherapy or hormonal therapy, and who participated in a fenretinide BC prevention trial as untreated controls. Blood samples were collected 3 months (median) after surgery; plasma samples, stored at –80°C, were radioimmunoassayed for testosterone. Median follow-up was 14 years. The main end point was any cancer event. Event-free survival was estimated by the Kaplan-Meier method. Hazard ratios (HRs) of events by testosterone level were estimated by the Cox model, adjusting for age, tumor size, and histology.
Results: Patients with high testosterone ( Conclusion: High plasma testosterone strongly predicts poorer prognosis in postmenopausal BC patients not administered adjuvant therapy. Testosterone levels should be determined as part of the prognostic work-up.
The risk of developing breast cancer (BC) is related to events of reproductive life and lifestyle factors that modify plasma levels of endogenous sex hormones.1-2 Soon after the discovery of sex hormones, in the 1930s, it was suggested that BC risk was related to endogenous estrogen levels.3 Later in vitro and in vivo studies showed that estrogens increase the proliferation of normal and cancerous breast epithelium cells.4-5 In the 1970s, other research had indicated that BC risk was increased in women with excess ovarian androgen production, and also with chronic anovulation and associated reduction of luteal-phase progesterone.6-7 Large prospective cohort studies on postmenopausal women now make it clear that high serum levels of both estrogens and androgens are associated with increased BC risk. A reanalysis of nine prospective studies found that the strengths of these associations were similar, with relative risks estimated of 2 to 3 for women in the highest quintile of hormone level compared with those in the lowest quintile8; furthermore, high testosterone was a marker of increased risk irrespective of estradiol levels.8 These results were supported by the large European Prospective Investigation into Cancer and Nutrition (EPIC) study and by the Nurses' Health study.9-10 Before menopause, the key hormonal imbalances that precede BC development are high serum androgens11-13 and low luteal-phase progesterone.11-12 As regard prognosis, high urinary testosterone was found to be associated with poor prognosis in BC patients.14-15 More recently, the finding that antiestrogen treatments are effective in preventing BC recurrence16 has further established the role of estrogens in BC prognosis. Our own study17 on 110 postmenopausal BC patients with 5.5 years of follow-up found that high serum testosterone was an important predictor of BC progression; serum estradiol was also found to be significantly associated with poor prognosis, but its effect disappeared after adjusting for serum testosterone.17 We also found that high serum testosterone was related to the presence of metabolic syndrome, and that presence of metabolic syndrome was strongly associated with BC progression.18 These data suggest that high circulating testosterone is a marker of a more general dysmetabolic condition that favors cancer development and progression. Metabolic syndrome19-20 and its components (central adiposity, impaired fasting glucose, elevated blood pressure, high triglyceride, and low high-density lipoprotein cholesterol) have been found to be associated with the occurrence21-24 and progression25-27 of several neoplasms. In 2003, after the results of our previous studies,17-18 we designed a new study to investigate the role of high testosterone in predicting new cancer events in BC patients. This new study took advantage of a larger independent set of postmenopausal BC patients with longer follow-up. The set of patients considered was the untreated control group of a clinical trial28 performed to test the efficacy of the retinoid fenretinide in preventing BC recurrence. This article presents the findings of this new study.
Study Patients We used the data on the untreated postmenopausal patients recruited at the Istituto Nazionale dei Tumori (INT; Milan, Italy) to the fenretinide BC prevention trial.29 This trial began on March 1, 1987, and accrual closed on July 31, 1993. Trial design, protocol, and results have been published elsewhere.28-30 Patients eligible for inclusion were operated on for T1N0M0 or T2N0M0 BC; did not receive adjuvant chemotherapy or hormone therapy; and had no new cancer event after surgery. At baseline, patients were assessed for metastases by chest x-ray, bone scan, blood tests for liver function, and liver ultrasonography, and, for contralateral BC, by mammography. Those recruited also had normal metabolic function tests and normal erythrocyte, leukocyte, and platelet counts. Postmenopausal status was defined as amenorrhea for more than 1 year before recruitment. Patients who had undergone hysterectomy without ovariosalpingectomy were considered postmenopausal if they were older than 50 years at enrollment. At baseline, patients donated blood for retinol measurements and other ancillary studies.31-32 The samples were conserved at –80°C; no thawing accident occurred during storage. In view of the small quantities of cryopreserved plasma available and the fact that testosterone measurements are more reliable than estradiol measurements in postmenopausal women,33-34 only testosterone was assayed for this study. Material was available to determine testosterone in 194 of the 235 control patients prospectively enrolled in the fenretinide trial.28 Samples from these 194 women (age: mean, 58.7 ± 5.0 years; range, 48 to 70 years) at recruitment had been taken at median of 2.8 months after surgery (89% within 12 months; 37% within a month); for the 10% who were recruited later, samples were taken 12 to 55 months after surgery. Life status was checked annually. At July 31, 2003 (end of follow-up), 15 years after the initiation of the trial, no cohort member had been lost to life-status follow-up. However 36 women (19%) had been lost to clinical follow-up (8% lost at 10 years). These women were not covered by a cancer registry or included in other clinical files. Clinical follow-up consisted of an annual check with mammography and chest x-ray, and a biannual visit including clinical examination and blood tests; bone scan was programmed every 18 months.29 During the 15-year follow-up, no participant received adjuvant chemotherapy or hormone therapy. All causes of death were recorded; 46 deaths occurred, 41 resulting from cancer (39 from BC). All participants who died as a result of cancer had a new cancer event before death and were retained in the survival analysis to the date of the new event. At the end of follow-up, median potential follow-up35 was 13.9 years (interquartile range, 12.8 to 14.8 years). The main end point was any cancer event (BC event or second primary at nonbreast site). BC events comprised local relapse, regional relapse, distant metastasis, contralateral primary BC, and ipsilateral primary BC unrelated to the first. Secondary end points were any BC event and second primary at nonbreast site. Lobular carcinoma in situ was not considered an event. Death from causes other than cancer without previous cancer event was not considered an event.
Blood Sample Storage and Testosterone Assay
Statistical Analysis The following variables were evaluated as possible covariates: age at recruitment (continuous variable), size of first primary BC (dichotomized as pT1 v pT2 according to the 1987 TNM classification36; one woman originally classified as pT1-pT2 was considered pT2), histology (infiltrating ductal carcinoma v other), time between surgery and blood sampling, and type of treatment (breast-conserving surgery v mastectomy). As expected,37 there was a weak inverse relationship between testosterone levels and age; therefore, age at recruitment was considered a potential confounder and included in all models. Cancer size and histology had modest influences on HR estimates and were retained in the final models. By contrast, type of primary treatment and time between surgery and blood sampling did not substantially influence HRs and were excluded from final models. At the time of recruitment, hormone-receptor status was determined in a selected group of women; information was missing in 20% of the cohort and was not considered in the main analyses.
To calculate the sample size, we scrutinized the results of our previous study (to our knowledge, the only one available on testosterone and BC progression) in which high testosterone had an HR of 7.2 (95% CI, 2.4 to 21.4) for BC progression versus low testosterone and 5-year event-free survival was 87% in the low testosterone group.17 We calculated that 188 women would be sufficient to detect an HR of 2.5 for any cancer event in the high- versus low-testosterone group, with 85% power and an
Ninety-five percent CIs were estimated for all HRs. All P values refer to two-sided statistical tests; differences with P
Table 1 shows the baseline characteristics of the 194 women dichotomized by testosterone levels. Except for cancer size, the women in the two testosterone groups were well balanced, although no differences were significant by  2 test. The 55- to 59-year age group contained the highest proportions of women (33% in the < 0.40 ng/mL group and 35% in the  0.40 ng/mL group); there were few women in the youngest (45 to 49 years; 4%) and oldest (65+ years; 12% and 9%) age groups. A total of 155 (75% and 85%) patients had stage I BC (pT1N0M0), 120 (62%) had infiltrating ductal carcinoma, with or without intraductal component. Most (72% and 76%) underwent breast-conserving surgery.
Patients with high plasma testosterone ( the median of 0.40 ng/mL) had significantly worse (P = .004) event-free survival than did patients with plasma testosterone below the median (Fig 1). The advantage for the low-testosterone group became evident from the third year of follow-up, as illustrated by the event-free survival curves (Fig 1). Five-year event-free survival was 83% in the low-testosterone group and 76% in the high-testosterone group; 10-year event-free survival was 70% versus 52%; 15-year event-free survival was 67% versus 36% (Fig 1).
Table 2 shows all cancer events and vital status at the end of follow-up according to testosterone level. Eighty women (41%) had no event, 50 (63%) in the low- and 30 (37%) in the high-testosterone group. Sixty-three patients (32%) had a BC event: 26 (41%) in the low- and 37 (59%) in the high-testosterone group. Fifteen patients had a second nonbreast primary, four (27%) in the low- (one each stomach, lung, and kidney cancers, and one leukemia) and 11 (73%) in the high-testosterone group (one each oral cavity, esophageal, liver, lung, endometrial, ovarian, and parotid cancers; two each colon cancer and melanoma). Of 46 deaths—39 from BC—20 (44%) were in the low- and 26 (56%) in the high-testosterone groups.
Table 3 shows age-adjusted HRs and HRs adjusted for age, tumor size, and histology, where appropriate, for different events. For all end points, women with high testosterone had significantly greater HRs than did low-testosterone women. In the high-testosterone group, HRs were 2.05 (95% CI, 1.28 to 3.27) for any cancer event, 1.77 (95% CI, 1.06 to 2.96) for any BC event, and 3.74 (95% CI, 1.19 to 11.80) for second primary at nonbreast site.
When testosterone levels were categorized into tertiles, HRs showed a significant linear trend: The multivariable adjusted HRs for increasing tertiles were 1.0, 2.0 (95% CI, 1.09 to 3.65), and 2.41 (95% CI, 1.33 to 4.35) for any cancer event (P for the trend = .004); 1.0, 1.83 (95% CI, 0.96 to 3.51), and 1.98 (95% CI, 1.03 to 3.81) for any BC event (P for the trend = .041); and 1.0, 3.36 (95% CI, 0.64 to 17.6), and 5.46 (95% CI, 1.16 to 25.8) for second primary cancer at nonbreast site (P for the trend = .025).
The results of this study are in full accord with our previous finding17 of an association between high endogenous testosterone levels and worse prognosis for postmenopausal BC patients. In this larger cohort with longer follow-up, women with high plasma testosterone level had significantly lower 15-year event-free survival after breast surgery than did those with low testosterone. High endogenous sex hormones, particularly testosterone, are established risk factors for developing BC.8-13 However, to our knowledge, no other prospective studies indicating an association between sex hormones and BC prognosis have been published (except our previous one17). We investigated testosterone but not estrogens. Interpretations of the results of prospective studies that analyzed the effects of estrogens and testosterone on BC risk in the same model have been contrasting. Some studies suggested that testosterone might be more strongly associated with BC risk than estradiol8,39; others indicated that the contribution of androgens to BC risk was largely due to their role as estrogen precursors.40 In this study, 11 (73%) of the 15 primary cancers at nonbreast sites developed in the high-testosterone group. In addition to a case of endometrial carcinoma, which is known to be related to both estrogens and androgens,41-42 these second primaries included seven other tumors for which a relationship with reproductive factors or sex hormones has been hypothesized, including melanoma,43 colon cancer,44 ovarian cancer,45 liver cancer,46 and lung cancer.47 For none of these cancer sites, however, has a firm etiologic relationship with sex hormones been established. It is unclear whether testosterone per se is directly responsible for the observed poor prognosis or is just a marker of a general metabolic imbalance that provides a milieu in which cancer cell proliferation in the breast or another site is facilitated. In a recent study,18 we found that presence of metabolic syndrome was strongly associated with BC progression, and that high serum testosterone was related to the presence of metabolic syndrome. We also found, however, that, irrespective of metabolic syndrome status, women with high testosterone had poorer prognosis,18 indicating an independent role of testosterone in BC progression. A number of limitations of the study must be considered. During the 15-year follow-up, 36 women were lost (19%; Table 2). We expected approximately 10 deaths in this group, but know that all were alive at the end of follow-up; they therefore constitute a good prognosis subgroup compared with compliant women. Nevertheless, this subgroup showed no testosterone selection (17 had low and 19 high testosterone). The noncompliance of these patients should have no systematic effect on the event-free survival curves because dropouts were spread over entire follow-up period (8% lost at 10 years) and occurred at the same rate in the low- and high-testosterone groups. Furthermore, we found no significant differences in age, tumor size, histology, and treatment between dropouts and compliers (data not presented). We made retrospective use of data from a clinical trial designed two decades ago; as a result, another limitation is lack of systematic information on more recently established prognostic factors such as hormone receptor, HER-2, and p53 expression in cancer specimens. At the time of recruitment, hormone-receptor status was not determined in all women, and those in whom it was determined (158 women, 127 compliant) are not a random subgroup of the entire cohort. When estrogen-receptor status was included in a multivariable analysis, adjusted HRs in relation to testosterone did not change substantially (data not shown). It is also important to note that study participants did not receive adjuvant therapy. Today's hormone receptor–positive patients would receive hormone therapy, and selected patients would be offered chemotherapy; the generalizability of our findings may be limited for this reason. Finally, participants were recruited with varying intervals between surgery and blood sampling. However, this did not affect our results because mean testosterone levels did not significantly change with time between surgery and blood sampling, and the time to sampling did not substantially influence HRs (data not shown). To conclude, these results corroborate our previous finding17 that endogenous testosterone levels strongly influence the prognosis in women operated on for BC. The implication is that testosterone assays should be determined as part of the prognostic work-up in postmenopausal women with this disease.
The author(s) indicated no potential conflicts of interest.
Conception and design: Andrea Micheli, Giorgio Secreto, Franco Berrino, Elisabetta Venturelli, Giuseppe De Palo, Franca Formelli Financial support: Andrea Micheli Provision of study materials or patients: Maria G. Di Mauro, Elena Cavadini, Franca Formelli Collection and assembly of data: Tiziana Camerini, Maria G. Di Mauro Data analysis and interpretation: Andrea Micheli, Elisabetta Meneghini, Giorgio Secreto, Elisabetta Venturelli, Adalberto Cavalleri, Franca Formelli Manuscript writing: Andrea Micheli, Elisabetta Meneghini, Franco Berrino, Giuseppe De Palo, Franca Formelli Final approval of manuscript: Andrea Micheli, Elisabetta Meneghini, Giorgio Secreto, Franco Berrino, Elisabetta Venturelli, Adalberto Cavalleri, Tiziana Camerini, Maria G. Di Mauro, Elena Cavadini, Giuseppe De Palo, Umberto Veronesi, Franca Formelli
We thank Don Ward for language assistance and the Fenretinide Breast Cancer Prevention Trial participants for their continuing cooperation.
published online ahead of print at www.jco.org on June 4, 2007. Supported by the Italian Association for Cancer Research (ref. 47/03) and the US National Cancer Institute, US Department of Health and Human Services, National Institutes of Health, and the Italian National Research Council. Presented in part at the Reunião do Grupo para a Epidemiologia e o Registro do Cancro nos Países de Língua Latina, May 4-6, 2005, Lisbon, Portugal. Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.
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Copyright © 2007 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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ABSTRACT
INTRODUCTION
level of .05.
.05 were considered significant. The analyses were performed with the STATA statistical software package, release 7.0 (2001; Stata Corp, College Station, TX). 
