Increased prevalence of colonic polyps and altered lymphocyte subset pattern in the colonic lamina propria in acromegaly

Growth hormone alters gross anatomy and morphology of the small and large intestines in age- and sex-dependent manners

PURPOSE

Growth hormone (GH) has an important role in intestinal barrier function, and abnormalities in GH action have been associated with intestinal complications. Yet, the impact of altered GH on intestinal gross anatomy and morphology remains unclear.

METHODS

This study investigated the influence of GH signaling on gross anatomy, morphology, and fibrosis by characterizing the small and large intestines in male and female bovine growth hormone transgenic (bGH) mice and GH receptor gene-disrupted (GHR-/-) mice at multiple timepoints.

RESULTS

The length, weight, and circumference of the small and large intestines were increased in bGH mice and decreased in GHR-/- mice across all ages. Colon circumference was significantly increased in bGH mice in a sex-dependent manner while significantly decreased in male GHR-/- mice. Villus height, crypt depth, and muscle thickness of the small intestine were generally increased in bGH mice and decreased in GHR-/- mice compared to controls with age- and sex-dependent exceptions. Colonic crypt depth and muscle thickness in bGH and GHR-/- mice were significantly altered in an age- and sex-dependent manner. Fibrosis was increased in the small intestine of bGH males at 4 months of age, but no significant differences were seen between genotypes at other timepoints.

CONCLUSION

This study observed notable opposing findings in the intestinal phenotype between mouse lines with GH action positively associated with intestinal gross anatomy (i.e. length, weight, and circumference). Moreover, GH action appears to alter morphology of the small and large intestines in an age- and sex-dependent manner.

Acromegaly and Colorectal Neoplasm: An Update

Acromegaly is a systemic disease caused by excessive inappropriate secretion of GH and IGF-I levels, resulting in many systemic complications, including cardiovascular, respiratory, metabolic diseases, and a possible increased risk of some neoplasias. Although many studies on acromegaly and cancer remain uncertain, most data indicate that colorectal cancer (CRC) incidence is increased in this population. The exact mechanism involved in the role of GH-IGF-I axis in CRC has not been fully explained, yet it is associated with local and circulating effects of GH and IGF-I on the colon, promoting angiogenesis, cell proliferation, risk of mutation, inhibition of tumor-suppressor genes and apoptosis, thus facilitating a tumor microenvironment. Nevertheless, population-based studies present controversial findings on CRC incidence and mortality. All worldwide guidelines and expert consensuses agree with the need for colonoscopic screening and surveillance in acromegaly, although there is no consensus regarding the best period to do this. This review aims to analyze the existing data on CRC and acromegaly, exploring its pathophysiology, epidemiological studies and their limitations, colonic polyp characteristics, overall cancer and CRC incidences and mortality, risk factors for colon cancer pathophysiology, and recommendation guideline aspects.

Health-Related Complications of Acromegaly-Risk of Malignant Neoplasms

The issue of increased risk of benign and malignant neoplasms in patients with acromegaly remains the topic of debate from many years and was addressed by numerous studies. Many of them have shown increase in the cancer incidence. Among particular types of malignancies, thyroid, colorectal, and breast cancer are most commonly indicated as associated with acromegaly. Single reports denoted increase in prevalence of neoplasms of other organs such as kidney, bone or central nervous system. Cardiovascular and respiratory tract disorders were traditionally consider as main causes of mortality in acromegalic patients, accounting for about 60 and 25% of deaths, respectively. However, according to a number of studies published over the current decade cancer became the most important cause of deaths. Aim of the current article was to review the literature concerning the risk of malignant neoplasms in acromegaly and its clinical implications.

Colonic Cancer and Acromegaly

Acromegaly results in a significantly increased morbidity and mortality due to cardiovascular and respiratory complications, as well as malignancies arising mainly from the colon. Furthermore, an increased lifetime risk of malignant transformation of pre-malignant colonic lesions relates to a worse overall prognosis from colorectal cancer, which is currently considered a major disease-related complication. In this review we provide some insight into colonic changes in this condition, summarize current knowledge and evidence on the use of colonoscopic screening in patients with acromegaly, and suggest a recommended screening protocol.

Cancer Incidence in Patients With Acromegaly: A Cohort Study and Meta-Analysis of the Literature

CONTEXT

Acromegaly has been associated with increased risk of cancer morbidity and mortality, but research findings remain conflicting and population-based data are scarce. We therefore examined whether patients with acromegaly are at higher risk of cancer.

DESIGN

A nationwide cohort study (1978 to 2010) including 529 acromegaly cases was performed. Incident cancer diagnoses and mortality were compared with national rates estimating standardized incidence ratios (SIRs). A meta-analysis of cancer SIRs from 23 studies (including the present one) was performed.

RESULTS

The cohort study identified 81 cases of cancer after exclusion of cases diagnosed within the first year [SIR 1.1; 95% confidence interval (CI), 0.9 to 1.4]. SIRs were 1.4 (95% CI, 0.7 to 2.6) for colorectal cancer, 1.1 (95% CI, 0.5 to 2.1) for breast cancer, and 1.4 (95% CI, 0.6 to 2.6) for prostate cancer. Whereas overall mortality was elevated in acromegaly (SIR 1.3; 95% CI, 1.1 to 1.6), cancer-specific mortality was not. The meta-analysis yielded an SIR of overall cancer of 1.5 (95% CI, 1.2 to 1.8). SIRs were elevated for colorectal cancer, 2.6 (95% CI, 1.7 to 4.0); thyroid cancer, 9.2 (95% CI, 4.2 to 19.9); breast cancer, 1.6 (1.1 to 2.3); gastric cancer, 2.0 (95% CI, 1.4 to 2.9); and urinary tract cancer, 1.5 (95% CI, 1.0 to 2.3). In general, cancer SIR was higher in single-center studies and in studies with <10 cancer cases.

CONCLUSIONS

Cancer incidence rates were slightly elevated in patients with acromegaly in our study, and this finding was supported by the meta-analysis of 23 studies, although it also suggested the presence of selection bias in some earlier studies.

THE PREVALENCE OF COLONIC POLYPS IN PATIENTS WITH ACROMEGALY: A CASE-CONTROL, NESTED IN A COHORT COLONOSCOPIC STUDY

OBJECTIVE

Acromegaly is associated with an increased risk of colonic polyps. The magnitude of such risk is controversial, and the characteristics that distinguish patients who develop polyps from those who do not are not well established. This study was performed to determine the prevalence of colonic polyps upon the diagnosis of acromegaly and to compare the clinical and biochemical features of patients with and without polyps.

METHODS

Out of 165 patients who underwent a full colonoscopy upon diagnosis of acromegaly, 53 were found to harbor colonic lesions (cases), whereas the remaining 112 were used as controls. Demographic, clinical, and biochemical characteristics were compared between the 2 groups.

RESULTS

The prevalence of colonic polyps was 32%, with an estimated relative risk of 6.21 (95% confidence interval [CI] 4.08-9.48). Adenomatous and nonadenomatous polyps were found in 22 and 31 patients, respectively. The most common location was the descending colon. Compared to patients without polyps, subjects with polyps were somewhat older and had significantly higher insulin-like growth factor-1 (IGF-1) levels and a higher prevalence of diabetes. Upon multivariate analysis, only IGF-1 level at diagnosis remained significantly associated with colonic polyps in general and with hyperplastic polyps in particular.

CONCLUSION

Acromegaly is associated with an elevated risk of developing colonic polyps, particularly, distally located hyperplastic lesions. Except for a higher IGF-1 level at diagnosis, no distinctive clinical or biochemical features can be found among those who develop polyps compared to those who do not.

ABBREVIATIONS

CI = confidence interval GH = growth hormone IGF-1 = insulin-like growth factor 1 IQR = inter-quartile range RR = relative risk ULN = upper limit of normal.

Prevalence of colonic polyp and its predictors in patients with acromegaly

BACKGROUND

There are conflicting data regarding the prevalence of colorectal polyp in patients with acromegaly.

SUBJECTS AND METHODS

Consecutive forty-seven acromegalic patients (21 men, 26 women), with a mean age of (40 ± 12 years) attending endocrinology outpatient department underwent full colonoscopy. All the patients underwent clinical and biochemical evaluation (glucose suppressed growth hormone (GH), Insulin-like growth factor-1 [IGF-1], fasting insulin, and glucose). The control group (n = 120) for colonoscopy was adult subjects undergoing evaluation for symptoms of irritable bowel syndrome. Clinical and biochemical parameters in acromegalic patients with colonic polyp were compared to those without a polyp.

RESULTS

Patients with acromegaly had significantly higher prevalence of colonic polyp as compared to control subjects (10.6% vs. 0.8%). None of the patients with polyp had skin tags. There was no significant difference between subjects with and without colonic polyp in duration of illness, basal, and glucose-suppressed GH and most recent IGF-1. Fasting blood sugar was significantly higher (P < 0.05) in adenoma group after adjusting for age, body mass index (BMI), and insulin levels. Patients in adenoma group showed a trend toward male gender and younger age as compared to those without adenoma.

CONCLUSIONS

Subjects with acromegaly as compared to control have a higher prevalence of colonic polyps. There was no association of polyps seen with age, BMI, skin tags, homeostasis model assessment of insulin resistance index, duration of disease, and basal and glucose-suppressed GH and IGF-1 levels. There were no specific predictive factors detected. Screening full colonoscopy is recommended in all cases with acromegaly.

Treatment Factors That Influence Mortality in Acromegaly

Acromegaly is a rare condition characterized by excessive secretion of growth hormone (GH), which is almost always due to a pituitary adenoma. Acromegaly is associated with significant morbidity such as hypertension, type 2 diabetes, cardiomyopathy, obstructive sleep apnoea, malignancy and musculoskeletal abnormalities. Acromegaly has also been associated with increased mortality in several retrospective studies. This review will focus on the epidemiological data relating to mortality rates in acromegaly, the relationship between acromegaly and malignancy, the role of GH and insulin-like growth factor-I in assessing the risk of future mortality, and the impact of radiotherapy and hypopituitarism on mortality.

Outcome of complications in acromegaly patients after long-term disease remission

Acromegaly patients suffer from pathologically high growth hormone (GH) and IGF-1 levels that in 99% of cases is due to a GH-producing pituitary adenoma. During active disease, GH excess is associated with a number of pathological conditions, such as hypertension, hypertrophic cardiomyopathy, sleep apnea, arthropathy, vertebral fractures and insulin resistance. After adequate treatment in the form of transsphenoidal surgery, radiotherapy, medical treatment or by a combination of these treatment modalities, several comorbid conditions improve considerably. However, despite long-term biochemical disease control, the prevalence of late manifestations of GH excess is high and significantly impair quality of life. In addition, there is evidence that adequate treatment is not able to normalize mortality risk in these patients. In this review, we critically evaluate the long-term consequences of acromegaly after treatment, focusing on comorbid conditions, quality of life and mortality. We also discuss ongoing challenges in the management of acromegaly patients.

The role of colonoscopic screening in acromegaly revisited: review of current literature and practice guidelines

INTRODUCTION

Acromegaly is a chronic, debilitating and disfiguring condition with a significantly increased morbidity and mortality due to cardiovascular, as well as respiratory complications. Patients with acromegaly are usually diagnosed at the age of 40, however, the duration of symptoms can vary from 5 to 10 years before the formal diagnosis is confirmed. Recent advances in the field of acromegaly have improved survival significantly. A strong association between acromegaly and premalignant colonic lesions and colon cancer has been highlighted. Furthermore, patients with acromegaly have a greater lifetime risk of malignant transformation and a far worse overall prognosis from colorectal cancer, which is now considered a major disease related complication.

MATERIALS AND METHODS

A comprehensive search strategy was applied for the Medline/PubMed electronic database from its inception until April 2014. We considered all human research articles published in English, not classified as case report, editorial, comment, letter, or news.

CONCLUSION

Specific recommendations for large bowel endoscopic screening in patients with acromegaly have been proposed. In this comprehensive review we discuss the current state of knowledge and evidence on colonoscopic screening in patients with acromegaly illustrated by a case of aggressive colorectal cancer presenting late in a young woman with difficult to control acromegaly.

Synchronous esthesioneuroblastoma and growth-hormone-secreting pituitary macroadenoma: combined open and endoscopic management

Background Esthesioneuroblastoma is an uncommon malignant neoplasm that arises from the olfactory neuroepithelium. In this article we report a case of esthesioneuroblastoma presenting concomitantly with a growth-hormone (GH)-secreting pituitary macroadenoma. Results A 52 year old woman underwent surgery for suspected nasal polyps. Intralesional debulking of an intranasal tumor disclosed a low-grade esthesioneuroblastoma. Magnetic resonance imaging (MRI) demonstrated a large nasal and intracranial tumor, in addition to a separate sellar and suprasellar tumor. The patient was frankly acromegalic. She underwent a first-stage gross total resection of the esthesioneuroblastoma via a combined extended subfrontal and extended endonasal approach, followed by focused radiation therapy. She then returned for endoscopic removal of the GH-secreting pituitary macroadenoma. Conclusion The combined open and endoscopic management of this patient is described and a review of the literature presented. To our knowledge this is the first case of synchronous esthesioneuroblastoma and macroadenoma, in this case GH secreting, described in the literature.

Frequency of various types of neoplasia in a group of acromegalic patients

OBJECTIVE

To determine the frequency of colon cancer, primary hyperparathyroidism, thyroid tumor, and skin cancer in all acromegalic patients in follow-up at the Clinics Hospital - Botucatu Medical School, from 2005 to 2011.

SUBJECTS AND METHODS

These patients were evaluated retrospectively for colon cancer, primary hyperparathyroidism, dermatological, and thyroid tumors.

RESULTS

Of 29 patients included at the beginning of the study, two were excluded. Among 19 patients submitted to colonoscopy, one presented colon adenocarcinoma (5%). Thyroid nodules were present in 63% of patients, and papilliferous carcinoma was confirmed in two patients (7,7%). Four patients were confirmed as having primary hyperparathyroidism (15%). The most common dermatologic lesions were thickened skin (100%), acrochordons (64%), epidermal cysts (50%), and pseudo-acanthosis nigricans (50%). Only one patient presented basal cell carcinoma.

CONCLUSION

Although a small number of acromegalic patients was studied, our findings confirm the high frequency of thyroid neoplasias and primary hyperparathyroidism in this group of patients.

Colonic neoplasia in acromegaly: increased proliferation or deceased apoptosis?

Patients with acromegaly have higher prevalence of colorectal neoplasms. The pathogenetic mechanism is still unclear and may be related to sustained increase in serum GH-IGF1. We aimed to evaluate the proliferative and apoptotic markers in samples of colonic mucosa obtained during screening colonoscopic biopsy from patients with acromegaly and study their relationship to serum IGF-1 and GH levels. The study subjects included 32 patients with acromegaly (4 female), 10 healthy controls (irritable bowel syndrome) and 10 positive controls (non-acromegalic colonic adenocarcinoma). Patients with acromegaly were divided into two groups, active disease (AD) and disease in remission (AR). Two biopsies each were obtained during colonoscopy from the right colon, transverse colon and rectosigmoid region. All the polyps were biopsied and subjected to histopathological examination. Immunohistochemistry for proliferation marker (Ki-67) and apoptotic markers (caspase-3 and TdT-Mediated dUTP Nick-End Labeling (TUNEL) was carried out in the histopathological samples. Indices of proliferation were significantly different in patients with acromegaly as compared to healthy controls. The mean Ki-67 positivity was 45.1 ± 17.7% in AD and 45.6 ± 23.1% in AR, as compared to 10 ± 5% in healthy controls. While none of the healthy controls had Ki-67 positivity beyond the lower third of crypts, among patients with acromegaly 12/32 (37.5%) had mid-third positivity (P = 0.000) and 15/32 (46.8%) had full length of crypt positively (P = 0.00). Immunostaining for caspase-3 was negative in patients with acromegaly and healthy controls. TUNEL was strongly positive in patients with colonic adenocarcinoma but not in healthy controls and patients with acromegaly. IGF-1 levels were higher in those with Ki-67 positivity in the superficial mucosa. Patients with acromegaly have increased proliferation of colonic epithelial cells. Elevated levels of serum IGF1 are associated with increase proliferation in the superficial crypt cells.

Prevalence and recurrence rate of colonic lesions in acromegalic patients

Acromegaly is associated with an increased prevalence of colonic polyps. The aim of this study was to evaluate the prevalence and recurrence rate of colonic polyps in acromegalic patients. Ninety-six acromegalic patients and 100 irritable bowel syndrome patients (IBS) were enrolled in the study. Twenty patients who were cured exclusively by surgery, and 20 patients that could not be hormonally controlled were re-examined colonoscopically after 36 months. Twenty-nine of 96 acromegalic patients (30.2%) had colonic polyps. In the IBS group, 10 (10.0%) had colonic polyps. The prevalence of colonic polyps was significantly higher in acromegaly. The group of acromegalic patients with and without polyps did not differ significantly with regard to plasma GH, IGF-I, fasting insulin levels and glycemic status. The presence of colonic polyps was correlated with increased patient age and male gender. We did not observe a difference in terms of polyp recurrence frequencies in the patients cured by surgery compared to uncontrolled patients. Acromegalic patients have a higher prevalence of colonic polyps than that of control subjects. We could not identify any factors that could predict polyps within the acromegalic patients - but age and male sex.

Repeated colonoscopic screening of patients with acromegaly: 15-year experience identifies those at risk of new colonic neoplasia and allows for effective screening guidelines

OBJECTIVE

It is suggested that patients with acromegaly have an increased risk of colorectal cancer and pre-malignant adenomatous polyps. However, the optimum frequency with which colonoscopic screening should be offered remains unclear.

DESIGN

To determine the optimum frequency for repeated colonoscopic surveillance of acromegalic patients.

METHODS

We retrospectively reviewed the case records of all patients with acromegaly seen in our centre since 1992: 254 patients had at least one surveillance colonoscopy, 156 patients had a second surveillance colonoscopy, 60 patients had a third surveillance colonoscopy and 15 patients had a fourth surveillance colonoscopy.

RESULTS

The presence of hyperplastic or adenomatous polyps was assessed in all patients, while one cancer was detected at the second surveillance. At the third surveillance, mean (+/-s.d.) serum IGF1 levels (ng/ml) in patients with hyperplastic polyps were significantly higher than those with normal colons (P<0.05). The presence of an adenoma rather than a normal colon at the first colonoscopy was associated with a significantly increased risk of adenoma at the second (odds ratio (OR) 4.4, 95% confidence interval (CI) 1.9-10.4) and at the third (OR 8.8, 95% CI 2.9-26.5) screens. Conversely, a normal colon at the first surveillance gave a high chance of normal findings at the second (78%) or third surveillance (78%), and a normal colon at the second colonoscopy was associated with normality at the third colonoscopy (81%).

CONCLUSIONS

Repeated colonoscopic screening of patients with acromegaly demonstrated a high prevalence of new adenomatous and hyperplastic colonic polyps, dependent on both the occurrence of previous polyps and elevated IGF1 levels.

Mortality in patients with pituitary disease

Pituitary disease is associated with increased mortality predominantly due to vascular disease. Control of cortisol secretion and GH hypersecretion (and cardiovascular risk factor reduction) is key in the reduction of mortality in patients with Cushing's disease and acromegaly, retrospectively. For patients with acromegaly, the role of IGF-I is less clear-cut. Confounding pituitary hormone deficiencies such as gonadotropins and particularly ACTH deficiency (with higher doses of hydrocortisone replacement) may have a detrimental effect on outcome in patients with pituitary disease. Pituitary radiotherapy is a further factor that has been associated with increased mortality (particularly cerebrovascular). Although standardized mortality ratios in pituitary disease are falling due to improved treatment, mortality for many conditions are still elevated above that of the general population, and therefore further measures are needed. Craniopharyngioma patients have a particularly increased risk of mortality as a result of the tumor itself and treatment to control tumor growth; this is a key area for future research in order to optimize the outcome for these patients.

OPPORTUNITY: a randomized clinical trial of growth hormone on outcome in hemodialysis patients

BACKGROUND

The mortality rate of maintenance hemodialysis (MHD) patients remains high. Measures of protein-energy wasting, including hypoalbuminemia, are strongly associated with their high mortality. Growth hormone (GH) may improve lean body mass (LBM) and serum albumin levels, and health-related quality of life (HRQoL), which are significantly and positively associated with survival in MHD patients. The OPPORTUNITY Trial will examine whether GH reduces mortality and morbidity and improves overall health in hypoalbuminemic MHD patients.

HYPOTHESIS

The primary hypothesis is that daily recombinant human GH injections, compared with placebo, improve survival in hypoalbuminemic MHD patients. Secondary hypotheses are that GH improves morbidity and health, including number of hospitalized days, time to cardiovascular events, LBM, serum protein and inflammatory marker levels, exercise capacity, and HRQoL, and has a favorable safety profile.

DESIGN/MEASUREMENTS

This is a prospective, double-blind, multicenter, randomized clinical trial involving 2500 MHD patients, up to 50% with diabetes mellitus, from 22 countries. Patients are randomized in a 1:1 ratio to receive daily injections of GH (20 microg/kg per day) or placebo for 104 weeks. Key inclusion criteria include clinically stable and well-dialyzed (Kt/V > or =1.2) adult MHD patients with serum albumin <4.0 g/dl. Exclusion criteria include active malignancy, active proliferative or severe nonproliferative diabetic retinopathy, uncontrolled hypertension, chronic use of high-dose glucocorticoids, or immunosuppressive agents and pregnancy.

CONCLUSIONS

The OPPORTUNITY Trial is the first large-scale randomized clinical trial in adult MHD patients evaluating the response to GH of such clinical endpoints as mortality, morbidity, markers of body protein mass, inflammation, exercise capacity, and HRQoL.

Computed tomography colonography in acromegaly

INTRODUCTION AND AIM

Acromegalic patients have an increased risk for the development of colorectal cancer. For this reason, since 1996, screening colonoscopy has been recommended in all patients with acromegaly. The aim of our study was to assess the feasibility and to evaluate the results of computed tomography (CT)-colonography in acromegaly.

PATIENTS AND METHODS

We examined 23 acromegalic patients with no history of colorectal cancer (11 females and 12 males; age range 18-79 yr; disease duration range 1-15 yr) with CT-colonography. Twenty of them underwent traditional colonoscopy after the CT-colonography.

RESULTS

CT-colonography examination results were adequate in 17 of 23 cases (73%). CT-colonography found 12 polyps in eight patients, 95% confirmed by traditional colonoscopy. One polyp was a sigmoid cancer, and the diagnosis was confirmed at surgery. There were no polyps found by traditional colonoscopy that CT-colonography was not able to identify. The lesions were located in right colon (two), transversum (three), left colon (five), and sigmoid colon (two). Patient acceptance of the technique was good in 65%, medium in 20%, and poor in 15%.

CONCLUSION

For the first time we have demonstrated that CT-colonography has the potential ability to replace traditional colonoscopy in acromegalic patients. CT-colonography could be used as a screening modality for colon cancer in acromegaly.

Risk of colorectal neoplasm in patients with acromegaly: A meta-analysis

AIM: To examine the risk of colorectal neoplasm in acromegalic patients by meta-analyzing all relevant controlled studies.

METHODS: Extensive English language medical literature searches for human studies, up to December 2007, were performed using suitable keywords. Pooled estimates [odds ratio (OR) with 95% confidence intervals (CI)] were obtained using either the fixed or random-effects model as appropriate. Heterogeneity between studies was evaluated with the Cochran Q test whereas the likelihood of publication bias was assessed by constructing funnel plots. Their symmetry was estimated by the adjusted rank correlation test.

RESULTS: For hyperplastic polyps the pooled ORs with 95% CI were 3.557 (2.587-4.891) by fixed effects model and 3.703 (2.565-5.347) by random effects model. The Z test values for overall effect were 7.81 and 6.984, respectively (P < 0.0001). For colon adenomas the pooled ORs with 95% CI were 2.486 (1.908-3.238) (fixed effects model) and 2.537 (1.914-3.364) (random effects model). The Z test values were 6.747 and 6.472, respectively (P < 0.0001). For colon cancer the pooled OR with 95% CI was identical for both fixed and random effects model (OR, 4.351; 95% CI, 1.533-12.354; Z = 2.762, P = 0.006). There was no significant heterogeneity and no publication bias in all the above meta-analyses.

CONCLUSION: Acromegaly is associated with an increased risk of colorectal neoplasm.

Acromegaly: re-thinking the cancer risk

Acromegaly is characterized by sustained elevation of circulating growth hormone (GH) and insulin-like growth factor I (IGF-I), and is clearly associated with increased morbidity and overall mortality mainly due to cardiovascular, metabolic, and respiratory diseases. Although cancer-related mortality varies widely amongst retroperspective studies, it appears to be consistently elevated mainly in patients with uncontrolled disease. We review individual tumor types including neoplasms of the colon, breast, prostate, and thyroid where in vitro, animal studies, and studies in non-acromegalic cancer patients have established a role for the GH/IGF-I axis in tumor progression and possibly initiation. We highlight deficiencies in data in acromegalic patients where the evidence is less convincing. Instead, we explore the hypothesis that acromegaly, independent of hormone secretion, is a disease that heralds genetic and/or epigenetic alterations predisposing to cancer risk elsewhere.

Medical consequences of acromegaly: what are the effects of biochemical control?

This chapter discusses the effects of biochemical control of acromegaly on cardiovascular diseases, metabolic complications, respiratory abnormalities, malignancies and bone alterations. Acromegaly is associated with increased morbidity and mortality for cardiovascular and respiratory complications, whereas neoplasms seem to be a minor cause of increased risk of death. Other associated diseases are osteoarthritis, carpal tunnel syndrome, fatigue, visual abnormalities and reproductive disorders. Acromegaly results in premature death because of prolonged elevation of GH an IGF-I levels, and a strong biochemical control improves well-being and restores life expectancy to normal. The main goals of medical treatment of acromegaly include normalization of biochemical markers of disease activity, improvement in signs and symptoms of the disease, removal or reduction of tumor mass and preservation of pituitary function.

The association of fasting insulin concentrations and colonic neoplasms in acromegaly: a colonoscopy-based study in 210 patients

CONTEXT

Hyperinsulinemia is associated with colon carcinoma in the general population. PATIENTS with acromegaly are considered to be at risk for developing colonic lesions and typically have hyperinsulinemia.

OBJECTIVE

Our objective was to evaluate the role of fasting insulin levels on the prevalence of colonic adenomatous polyps or adenocarcinoma in acromegaly.

DESIGN

This is an analytical, observational, prospective study.

PATIENTS

A total of 210 patients (111 women, 99 men, age 20-82 yr) undergoing complete colonoscopy at diagnosis of acromegaly were included in this study.

RESULTS

Colonic lesions were found in 81 patients (38.6%), and consisted of hyperplastic polyps in 33 (15.7%), adenomatous polyps in 42 (20.0%), and adenocarcinoma in six patients (2.8%). Polyps were single in 22 cases (27.1%). Fasting insulin levels were significantly lower in patients without lesions (16.0 +/- 7.5 mU/liter) than in patients with hyperplastic polyps (22.4 +/- 8.8 mU/liter; P < 0.01), adenomatous polyps (38.0 +/- 15.9 mU/liter; P < 0.0001), and adenocarcinoma (59.0 +/- 30.6 mU/liter; P < 0.0001). Fasting insulin levels were also lower in patients with hyperplastic polyps than in those with adenomatous polyps (P < 0.01). The odds ratio for harboring colonic adenomas was 14.8 (95% confidence interval 4.4-51.2; P < 0.0001) and 8.6 times higher (95% confidence interval 2.8-29.0; P < 0.0001) in patients with fasting insulin levels in the upper tertile [>/=27.1 mIU/liter (n = 28)] compared with the lower [</=12.1 mIU/liter (n = 40)] and middle tertiles [>12.1 to <27.1 mIU/liter (n = 74)], respectively.

CONCLUSION

An increase in fasting insulin levels is associated with an 8.6- to 14.8-fold increased risk of presenting with colonic adenomas in acromegaly.

Growth hormone receptor expression is up-regulated during tumorigenesis of human colorectal cancer

BACKGROUND

The aim of the present study was to analyze the expression of growth hormone receptor (GHR) in the colorectal adenoma-carcinoma sequence to determine whether its expression correlates with the various stages of cancer transformation.

METHODS

GHR distribution was assessed by immunohistochemistry and semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) in normal, premalignant, and malignant colorectal lesions.

RESULTS

Most of the normal mucous tissues and hyperplastic polyps showed no or weak immunoreactivity for GHR. In contrast, most of the adenoma and adenocarcinoma samples reacted strongly or moderately with monoclonal GHR antibodies. In RT-PCR, amplified fragments of the expected sizes (247bp) were detected in 90 of 90 samples examined, and the semiquantitative RT-PCR result showed an up-regulation of GHR mRNA expression during the polyp-adenoma-carcinoma sequence, which was consistent with the immunohistochemical results.

CONCLUSIONS

Our results suggest that growth hormone/GHR plays a role in the development of colorectal carcinoma.

Cancers associated with acromegaly

Acromegaly is characterised by excessive levels of circulating growth hormone and its tissue mediator, insulin-like growth factor (IGF)-I. Prior to effective treatment and lowering of growth hormone and IGF-I, the majority of patients with the disease died by the age of 60 years, largely due to diabetes mellitus, cardiovascular and cerebrovascular diseases. More recently, it has become apparent that patients with acromegaly may also have an increased prevalence of colorectal adenomas and cancer. This may be due to elevated IGF-I, which is implicated in the development of sporadic colorectal cancer, and environmental factors, such as the bile acid deoxycholic acid, the levels of which are also increased in acromegaly. There is some evidence to suggest that breast and prostatic malignancies might also be increased in acromegaly. However, these associations have been based mostly on small epidemiological surveys and circumstantial evidence. Large-scale epidemiological studies are required to clarify this issue.

Apoptosis is reduced in the colonic mucosa of patients with acromegaly

BACKGROUND

Patients with acromegaly have an increased risk of developing colonic tumours; reduced apoptosis is considered a leading mechanism in tumorigenesis. GH and IGF-1 decrease apoptosis in several cell lines including human colonic adenocarcinoma, but it is unknown whether epithelial cells of colonic mucosa of patients with acromegaly have reduced apoptosis.

AIM

The aim of the study was to evaluate the degree of apoptosis in a cross-sectional study, in biopsy samples of colonic mucosa obtained from patients with acromegaly.

PATIENTS AND METHODS

Eleven patients with active, untreated acromegaly (AcroUntr), 16 patients with acromegaly in remission (AcroRem) and 23 controls were enrolled in the study. Samples of colonic mucosa were obtained during colonoscopy; apoptosis was evaluated by either DNA fragmentation or terminal deoxynucleotidyl transferase assay.

RESULTS

Apoptotic cells were 60.0 +/- 2.5% in samples of colonic mucosa of controls, 62.0 +/- 3.4% in those from patients with AcroRem (P = ns vs. controls), and 39.0 +/- 4.1% in those from patients with AcroUntr (P < 0.0001 vs. the other groups). Apoptosis was inversely related to serum IGF-I (r = 0.771, P < 0.001) or GH (r = 0.404, P = 0.05) levels and less to the estimated duration of disease (r = 0.384, P = 0.07). PPARgamma is considered to be a tumour suppressor gene the expression of which might be involved in colonic tumorigenesis. The expression of PPARgamma was lower in the colonic mucosa of patients with AcroUntr (2845 +/- 947 transcripts) than in that of controls (35 200 +/- 2450 transcripts) or AcroRem (29 547 +/- 3650 transcripts) (P < 0.005). The recovery of PPARgamma expression was associated with apoptosis in most cells. The lower degree of apoptosis in patients with AcroUntr was associated with a reduced expression of the antiapoptotic Bax protein.

CONCLUSION

In conclusion, patients with AcroUntr have reduced apoptosis in colonic mucosa that is apparently reversed after acromegaly is cured. It is conceivable that reduced apoptosis may represent an early event in colonic tumorigenesis of patients with acromegaly.

Acromegaly and cancer

In recent years, it has become increasingly recognized that acromegaly is associated with an increased prevalence of colorectal cancer and pre-malignant tubular adenomas. The aetiology of these tumours is unknown but is likely to reflect increased levels of both insulin-like growth factor I (IGF-I), which is implicated in the development of sporadic colorectal cancer, and environmental factors, such as the bile acid deoxycholic acid. There is also evidence to suggest that the prevalence of breast and perhaps haematological malignancies might be increased in acromegaly, although these associations have been based on mostly small epidemiological surveys and clarification will come in the future once large-scale epidemiological studies have been completed.

Risk of colorectal neoplasm in patients with acromegaly and its relationship with serum growth hormone levels

OBJECTIVES

Acromegalics have been reported to be at an increased risk of colorectal neoplasm. However, the magnitude of the risk is still controversial and the mechanism has not been fully investigated. In this study, we attempted to determine the magnitude of the association between acromegaly and colorectal lesions after taking into account age, gender, smoking status, and treatment status. In addition, we assessed the relationship between colorectal lesions and serum growth hormone (GH) levels in acromegalics.

METHODS

We conducted a case-control study by using 19 consecutive untreated patients (male:female = 11:8) who were newly diagnosed with acromegaly between 1990 and 2000. All patients underwent colonoscopy and received a histological diagnosis of colorectal lesions. Prevalence of hyperplastic polyp, adenoma, and carcinoma were compared with the prevalence in 76 controls matched for gender, age, and smoking status. Serum GH levels were compared between acromegalic patients with and without each type of colorectal lesion.

RESULTS

The prevalence of hyperplastic polyp, adenoma, and carcinoma were significantly higher in the acromegalic patients compared to the controls (p < 0.05, odds ratios; 8.3, 4.2, and 9.8, respectively). In acromegalics, the presence of hyperplastic polyps and carcinomas were significantly associated with higher serum GH levels after adjusting for the other lesions and age (p < 0.05).

CONCLUSIONS

After controlling for age, gender, smoking status, and treatment status, acromegaly was associated with significantly higher prevalence of colorectal hyperplastic polyp, adenoma, and carcinoma. High serum GH levels may be associated with the presence of hyperplastic polyp and carcinoma.

Determination of large bowel length and loop complexity in patients with acromegaly undergoing screening colonoscopy

BACKGROUND

Patients with acromegaly are at moderately increased risk of developing colorectal cancer and may be considered for screening colonoscopy. In turn, large bowel dimensions may be increased in these patients, factors that predict for increased risk of serious complications such as perforation.

OBJECTIVE

To evaluate this risk potential, we measured large bowel length and loop complexity using magnetic endoscopic imaging (MEI).

DESIGN

Case-control study in 25 unselected patients with acromegaly (mean age 56 years) vs. 41 nonacromegalic controls (mean age 60 years) undergoing screening colonoscopy.

MEASUREMENTS

MEI parameters were determined and age- and sex-adjusted mean differences calculated. The dependency of total large bowel length on various demographic and disease-related factors (e.g. GH exposure, IGF-I and IGFBP-3 concentrations) was assessed using regression techniques.

RESULTS

Total large bowel length was increased by 20%[95% confidence interval (CI) 9-31%] in patients with acromegaly compared with controls (unadjusted and adjusted; P-values < 0.001). Acromegaly was also associated with increased time taken to reach the caecum (P = 0.01) and increased pelvic loop complexities (5/25 vs. 1/41, Fisher's exact test: P = 0.03). Total large bowel length was predicted by age at colonoscopy (P = 0.003) and patient height (P = 0.03), but not by surrogate biochemical markers of disease activity.

CONCLUSIONS

Acromegaly is associated with increased large bowel length and loop complexity making colonoscopy technically challenging, and theoretically increasing the risk of serious complications. Patients need to be counselled accordingly, and appropriate resources with experienced staff allocated.

Growth Hormone/Insulin-Like Growth Factor–I System and Connective Tissues: Basic Aspects and Clinical Implications

This article reviews basic and clinical aspects of the effects of growth hormone and insulin-like growth factor-I on the connective tissues.

Growth hormone inhibits apoptosis in human colonic cancer cell lines: antagonistic effects of peroxisome proliferator activated receptor-gamma ligands

GH has antiapoptotic effects on several cells. However, the antiapoptotic mechanisms of GH on colonic mucosa cells are not completely understood. Peroxisome proliferator activated receptor-gamma (PPARgamma) activation enhances apoptosis, and a link between GH and PPARgamma in the colonic epithelium of acromegalic patients has been suggested. We investigated the effects of GH and of PPARgamma ligands on apoptosis in colonic cancer cell lines. Colonic cells showed specific binding sites for GH, and after exposure to 0.05-50 nm GH, their apoptosis reduced by 45%. The antiapoptotic effect was due to either GH directly or GH-dependent local production of IGF-1. A 55-85% reduction of PPARgamma expression was observed in GH-treated cells, compared with controls (P < 0.05). However, treatment of the cells with 1-50 microm ciglitazone (cig), induced apoptosis and reverted the antiapoptotic effects of GH by increasing the programmed cell death up to 3.5-fold at 30 min and up to 1.7-fold at 24 h. Expression of Bcl-2 and TNF-related apoptosis-induced ligand was not affected by either GH or cig treatment, whereas GH reduced the expression of Bax, which was increased by cig treatment. In addition, GH increased the expression of signal transducer and activator of transcription 5b, which might be involved in the down-regulation of PPARgamma expression. In conclusion, GH may exert a direct antiapoptotic effect on colonic cells, through an increased expression of signal transducer and activator of transcription 5b and a reduction of Bax and PPARgamma. The reduced GH-dependent apoptosis can be overcome by PPARgamma ligands, which might be useful chemopreventive agents in acromegalic patients, who have an increased colonic polyps prevalence.

High prevalence of hyperplastic colonic polyps in acromegalic subjects

We evaluated the prevalence and features of colonic polyps in a population of acromegalic subjects, compared to a control group of patients with irritable bowel syndrome (IBS). Colonic polyps were found in 30 acromegalic subjects (40%) and in 10 controls (13%) (P < 0.0001). Among the acromegalic patients, polyps were of the hyperplastic type in 27 subjects (90%) and adenomatous in 3 (10%). In the control group, polyps were hyperplastic in nine subjects (90%) and adenomatous in one (10%). We also observed a significant association (P < 0.0001) between the presence of hyperplastic polyps and the older age in both the acromegalic and the control groups. There were no differences between the two groups regarding sex, site, size, or macroscopic and histological types of polyps. Acromegalic patients have a higher prevalence of colonic hyperplastic polyps than IBS subjects, while the prevalence of adenomatous polyps is similar in the two groups.

Systemic complications of acromegaly: epidemiology, pathogenesis, and management

This review focuses on the systemic complications of acromegaly. Mortality in this disease is increased mostly because of cardiovascular and respiratory diseases, although currently neoplastic complications have been questioned as a relevant cause of increased risk of death. Biventricular hypertrophy, occurring independently of hypertension and metabolic complications, is the most frequent cardiac complication. Diastolic and systolic dysfunction develops along with disease duration; and other cardiac disorders, such as arrhythmias, valve disease, hypertension, atherosclerosis, and endothelial dysfunction, are also common in acromegaly. Control of acromegaly by surgery or pharmacotherapy, especially somatostatin analogs, improves cardiovascular morbidity. Respiratory disorders, sleep apnea, and ventilatory dysfunction are also important contributors in increasing mortality and are advantageously benefitted by controlling GH and IGF-I hypersecretion. An increased risk of colonic polyps, which more frequently recur in patients not controlled after treatment, has been reported by several independent investigations, although malignancies in other organs have also been described, but less convincingly than at the gastrointestinal level. Finally, the most important cause of morbidity and functional disability of the disease is arthropathy, which can be reversed at an initial stage, but not if the disease is left untreated for several years.

Colonic polyps of acromegalic patients are not associated with mutations of the peroxisome proliferator activated receptor gamma gene

Peroxisome proliferator activated receptor (PPAR)gamma plays a pivotal role in regulating adipocyte differentiation and metabolism, but also has an antiproliferative effect in several tissues, including colonic mucosa, where it is highly expressed. Loss-of-function mutations have been reported in about 10% of sporadic primary colon cancer. Acromegalic patients have an increased prevalence of colonic neoplasms and lower PPARgamma levels in the colonic mucosa. Thus, PPARgamma may act as a tumor suppressor gene, and its reduced expression or loss-of-function mutations may contribute to tumorigenesis. In this study the expression and mutations of the PPARgamma gene in the colonic polyps and mucosa outside polyps were investigated in 10 acromegalic and 17 non-acromegalic patients. PPARgamma expression was evaluated by RT-PCR. PPARgamma was expressed in each sample, but expression appeared to be lower in polyps than in mucosa outside polyps from either acromegalic or non-acromegalic patients. All exons of the PPARgamma gene were directly sequenced after PCR amplification: no mutations were found either in acromegalic or in non-acromegalic patients. In conclusion, the results of this preliminary study suggest that the lower expression of PPARgamma rather than somatic mutations of this gene is involved in colonic tumorigenesis.

IGFs and IGFBPs: role in health and disease

The insulin-like growth factors (IGFs), IGF-binding proteins (IGFBPs), and IGFBP proteases are the main regulators of somatic growth and cellular proliferation. IGFs are involved in growth pre-natally and post-natally. Dysregulation of the IGF axis can lead to growth disorders such as growth hormone deficiency and acromegaly. Pre-natally, this dysregulation can lead to IUGR or macrosomia. IGFs also have an important mitogenic action and play a role in tumorigenesis and cancer. These actions are regulated by co-interactions with IGFBPs, especially IGFBP-3. In addition to somatic growth and mitogenic activity, IGFs have hypoglycaemic and insulin sensitizing actions, and their dysregulation is involved in diabetes and its complications. In this chapter, we examine the role of IGFs and IGFBPs in growth, tumorigenesis and diabetes, and discuss treatment modalities for each disease involving the GH-IGF-IGFBP axis, including discussion of current in vitro and in vivo investigations in this field.

A comparison of the effects of pegvisomant and octreotide on glucose, insulin, gastrin, cholecystokinin, and pancreatic polypeptide responses to oral glucose and a standard mixed meal

Standard medical therapy for patients with acromegaly includes somatostatin analogs. Owing to the widespread expression of somatostatin receptors, these may be associated with unwanted effects, such as altered glucose tolerance and impaired gut hormone release. Pegvisomant is a novel pegylated GH analog that competes with wild-type GH for GH-receptor binding sites but contains a position 120, amino acid substitution that prevents functional GH receptor dimerization, a known prerequisite for GH signal transduction and generation of IGF-I. We have studied the short-term effects of these two therapies (pegvisomant 20 mg/d for 7 d and octreotide 50 microg thrice daily for 7 d) on glucose tolerance and stimulated gut hormone release in six healthy male volunteers in an open-label, random-order, cross-over study. Subjects were assessed at baseline (oral glucose tolerance test and standard mixed meal) and on d 6 and 7 of each therapy with a minimum washout of 2 wk between treatments. Area under the curve and peak responses were analyzed using one-way repeated-measures ANOVA (on ranks where appropriate). Pegvisomant had no effect on glucose tolerance or stimulated gut hormone response during an oral glucose tolerance test and a standard meal. In contrast, octreotide significantly increased fasting plasma glucose, lowered fasting plasma insulin, and led to deterioration in glucose tolerance; three subjects developed impaired glucose tolerance and one diabetes mellitus by World Health Organization criteria. Octreotide significantly impaired stimulated release of cholecystokinin, gastrin, insulin, and pancreatic polypeptide. In conclusion, pegvisomant, unlike octreotide, is not associated with deterioration in glucose tolerance and impairment of stimulated gut hormone release in normal males.

Lymphocyte subset pattern in acromegaly

Immune function in acromegalic patients has been poorly investigated. The aim of this study was to evaluate the main surface antigen clusters of circulating lymphocytes in acromegaly. One hundred patients with active acromegaly (55 women and 45 men, aged 20-70 yr) and 200 healthy subjects sex- and age-matched with the patients (110 women and 90 men, aged 20-70 yr) were enrolled in this study. All patients and controls were born and live in Southern Italy. No patient had received octreotide, bromocriptine or corticosteroids for at least 3 months before entering the study. The analysis of lymphocyte subset pattern was performed by flow cytometry and fluorescein isothiocyanate or phycoerythrin directly conjugated monoclonal antibodies specific for the cell surface antigen clusters (CD) representing T-cell population as a whole (CD3), T helpers (CD4), T suppressors (CD8), natural killer cells (CD16) and B-cell population as a whole (CD19). Acromegalics had significantly increased levels of CD3 (67.1+/-7.2 vs 64.3+/-8.8%; p=0.03) and CD4 (37.8+/-3.5 vs 36.4+/-4.3%; p=0.004) and decreased levels of CD8 (31.4+/-3.3 vs 33.7+/-8.2%; p<0.01) and CD19 (12.1+/-3.1 vs 15.2+/-5.1; p=0.01) without age-difference. The results of the current study demonstrate an increase in T-cell activity together with a decrease in B-cell activity in a very large series of patients with active acromegaly. These data further support the existence of abnormalities of the immune system in patients with chronic GH/IGF-1 excess.

Acromegaly

Acromegaly is a slow developing disease caused by hypersecretion of growth hormone and insulin-like growth factor 1. Increased morbidity and mortality associated with the disease make early diagnosis and treatment crucial. This article reviews the etiology, clinical manifestations, and diagnosis of acromegaly, with an emphasis on newly available therapeutic options.

Does the GH-IGF axis play a role in cancer pathogenesis?

Recent case-controlled studies have found increases in the serum levels of insulin-like growth factor-I (IGF-I) in subjects who had, or who eventually developed, prostate or premenopausal breast cancers. Since growth hormone (GH) increases IGF-I levels, concern has been raised regarding its potential role as a cancer initiation factor. The epidemiological studies, which indicate an association between serum IGF-I levels and cancer risk, have not established causality. In fact, several alternative explanations for the elevated serum IGF-I levels in cancer patients may be proposed based on human and animal models. First, an effect of IGF-I causing symptomatic benign tissue hyperplasia may result in an ascertainment bias leading to an initiation of procedures resulting in the diagnosis of asymptomatic cancers. Second, elevated serum IGF-I in cancer patients may originate within the tumor (as suggested by some animal studies). Thirdly, serum IGF-I may actually be a surrogate marker of tissue IGF-I levels or of nutritional factors, which are not under GH control and may be involved in cancer initiation. The role of GH in cancer initiation is further negated by the fact that in acromegaly, the incidence of cancer, other than possibly colonic neoplasia does not appear to be significantly increased. Furthermore, GH transgenic mice, with high IGF-I levels, do not develop breast, prostate, or colonic malignancies. It is known that IGFBP-3 can inhibit IGF action on cancer cells in vitro and also can induce apoptosis via an IGF-independent mechanism. Importantly, in addition to increasing IGF-I levels, GH also increases the serum levels of IGFBP-3 and serum IGFBP-3 levels have been shown to be negatively correlated with the risk of cancer in the above mentioned epidemiological studies and in a similar study on colon cancer. These studies suggest that cancer risk is increased in individuals in whom both high IGF-I levels and low IGFBP-3 levels are present. In subjects treated with GH, IGF-I and IGFBP-3 levels both rise together and are not within the elevated cancer-risk range, based on published studies. Long-term studies are needed to assess the potential risks, including the long-term cancer risk associated with GH therapy. These should take into account several factors, including the duration of exposure, the risk magnitude associated with the degree of serum IGF-I elevation, and the adjusted risk based on a concomitant increase in IGFBP-3 levels. Since GH treated patients often have sub-normal IGF-I serum levels, which normalize on therapy, one might predict that their cancer risk on GH therapy should not increase above the normal population. Until further research in the area dictates otherwise, on-going cancer surveillance and routine monitoring of serum IGF-I and IGFBP-3 levels in GH-recipients should be the standard of care. At present, the data that are available do not warrant a change in our current management of approved indications for GH therapy.

The prevalence and characteristics of colorectal neoplasia in acromegaly

An increased prevalence of colorectal neoplasia has been reported in acromegalic patients, and recommendations have been made for early colonoscopic screening and regular surveillance. This assumption, however, is frequently drawn from studies using selected control populations. To clarify colonoscopic management in these patients, we undertook a 2-center prospective screening colonoscopy study in 122 acromegalics (age range, 25-82 yr). In the absence of ideal age-matched controls, we calculated prevalence rates of occult adenocarcinomas and adenomas in the general population using cumulative data in the published literature from 8 autopsy studies (model 1, n = 3,559) and 4 screening colonoscopy studies (model 2, n= 810), applying linear regression models. Of the 115 patients with complete examinations, adenocarcinomas were discovered in 3 (2.6%), and at least 1 adenoma was found in 11, giving an overall prevalence of neoplasia of 12% (14 of 115). Prevalence rates for age bands 30-40, 40-49, 50-59, 60-69, and 70+ yr were 0%, 8%, 12%, 20%, and 21%, respectively. Compared with the 2 control models, the prevalence of occult colorectal cancer was not significantly increased (acromegalics vs. models 1 and 2, 2.6% vs. 2.3% and 0.9%), nor was there an increase in the prevalence of adenomas in any age band. Pathological characteristics showed some differences, in that adenomas in acromegalics tended to be right sided (68% vs. 57% and 56%), larger (for > or =10 mm, 27% vs. 13% and 9%), and of advanced histology (for tubulovillous, 27% vs. 4% and 22%). No associations were found between the presence of colonic neoplasia and the duration of disease, total GH exposure, cure status, and serum insulin-like growth factor I. This study has failed to demonstrate an increased prevalence of neoplasia in acromegalic patients compared with the expected prevalence in the general population and questions the need for an aggressive colonoscopic screening policy.

Insulin-like growth factor I and the development of colorectal neoplasia in acromegaly

Patients with acromegaly are at increased risk of colorectal neoplasia and, by analogy with high-risk nonacromegalic patients, may require regular colonoscopic screening. However, it is unknown whether the risk is equal in all patients or whether some should be regarded as carrying a particularly high risk. The aims of this study were: 1) to establish the natural history of colorectal neoplasia in acromegaly; 2) to establish which patients are at increased risk of developing neoplasia; and 3) to elucidate the influence of insulin-like growth factor I (IGF-I) in adenoma formation. A prospective colonoscopic evaluation of the development of new premalignant adenomas in the colon was performed in 66 patients with biochemically proven acromegaly who had previously undergone colonoscopic screening and removal of all visible polyps. Twenty-five patients (38%) had a total of 37 polyps detected at the second colonoscopy: nine (14%) had at least one adenoma, and 18 (27%) had one or more hyperplastic polyps (2 patients had both). The development of new adenomas, but not hyperplastic polyps, was associated both with elevated serum IGF-I (P < 0.005) and, to a lesser extent, with a previous adenoma at the original colonoscopy (P < 0.07). In summary, patients with acromegaly and in whom serum IGF-I remains elevated and/or who have had a previous adenoma should be regarded as having an especially high risk for the development of subsequent colorectal neoplasia. Serum IGF-I seems to be implicated in the development of colorectal neoplasia in acromegaly, although the exact mechanisms remain uncertain.

Pharmacotherapy or surgery as primary treatment for acromegaly?

In recent years important progress has been made in the management of acromegaly due to the availability of effective and well tolerated drugs and to improved surgical techniques, resulting in a broader choice of therapeutic interventions. Although surgery in the hands of an experienced surgeon still represents the primary option for the majority of patients, the new formulations of somatostatin analogues and dopamine agonists have partially modified the primary therapeutic approach to this severe and disabling chronic disease. Therapy with somatostatin analogues has been shown to reduce morbidity and the mortality rate in patients with acromegaly, and currently in some patients this medical approach may be preferable to surgery. Although in selected patients individualised pharmacotherapy might represent the primary therapy, trans-sphenoidal surgery of microadenomas and noninvasive macroadenomas remains the primary option, since the remission rate is very high and the costs are relatively low in comparison with lifelong therapy with somatostatin analogues. However, the treatment schedule in acromegaly should consider criteria additional to tumour size and invasiveness, such as the age and the general clinical condition of the patient. Presurgical treatment with somatostatin analogues has been reported to reduce surgical complications and time of hospitalisation after the operation. Moreover, a multidisciplinary team of well trained specialists is needed in order to guarantee the most optimal quality of life and life expectancy for patients with acromegaly.

Comparison of six months therapy with octreotide versus lanreotide in acromegalic patients: a retrospective study

OBJECTIVE

We analysed the effects of 6-months' treatment with octreotide s.c. and lanreotide-SR on circulating GH and IGF-I levels in acromegaly.

DESIGN

Open retrospective study.

PATIENTS

Thirty-eight patients with active acromegaly (plasma IGF-I levels greater than 2 standard deviations for age-matched controls and increased serum GH levels not suppressible by oral glucose load) were studied. All patients received s.c. octreotide at a dose of 150-600 microg/day for six months as first therapy and subsequently, lanreotide i.m., 30-60 mg either at 14 or 10 day intervals, for 6 months. A 3 months' washout was applied before starting lanreotide treatment.

MEASUREMENTS

Mean serum GH levels (from three samples), IGF-I, and clinical examination were performed before and 30, 60, 90 and 180 days after octreotide and lanreotide treatments. Safety tests, HbA1c and, thyroid function were evaluated every three months.

RESULTS

Circulating GH and IGF-I levels were significantly reduced (P < 0.001) after one, three and six months of both octreotide and lanreotide treatment. The absolute values were lower and the percent decrease in serum GH levels obtained after octreotide treatment was significantly greater, at all scheduled assessments, than after lanreotide (P < 0.01). Serum IGF-I levels during octreotide were significantly lower only after the first month of therapy (P < 0.01).

CONCLUSIONS

Our study shows that octreotide s.c. is able to induce an earlier reduction in IGF-I levels and a more marked reduction in GH levels than lanreotide. However, after six months of therapy the number of patients with safe GH levels and normal IGF-I age-matched levels, was similar with both drugs. Therefore we suggest that octreotide treatment be preferentially used in the short-term presurgical treatment, while lanreotide can be used in chronic therapy when better compliance is necessary.

Cancer in acromegaly

In recent years, it has become increasingly recognized that acromegaly predisposes to a variety of cancers, particularly colorectal and breast cancers, and perhaps haematological malignancies. However, these associations have been based mostly on small epidemiological surveys, and a propensity towards other malignancies might also become apparent in the future. This review assesses these three malignancies together with those of the thyroid and prostate, and discusses their pathogenesis, concentrating on the role of the growth hormone/insulin-like growth factor I (IGF-I) axis.

Growth-hormone and prolactin excess

The treatment of acromegaly and hyperprolactinaemia has been improved by the availability of effective and well-tolerated slow-release somatostatin analogues and dopamine agonists with long-lasting activity, such as cabergoline. The use of these drugs has extended the possibility of treatment to patients who would have responded poorly to the previously available compounds, such as octreotide or bromocriptine, and to those who were intolerant to pharmacotherapy. Moreover, the improvement in the management of acromegaly has enabled the reversal, at least partly, of cardiomyopathy and sleep apnoea, two important risk factors for morbidity and mortality in these patients.