Real-world experience with 11C-methionine positron emission tomography in the management of acromegaly.

BACKGROUND: L-[methyl-11C]-methionine-positron emission tomography (Met-PET) is a potentially important imaging adjunct in the diagnostic workup of pituitary adenomas, including somatotroph tumors. Met-PET can identify residual or occult disease and make definitive therapies accessible to a subgroup of patients who would otherwise require lifelong medical therapy. However, existing data on its use are still limited to small case series. Here, we report the largest single-center experience (n = 61) in acromegaly. METHODS: A total of 189 cases of acromegaly were referred to our national Met-PET service in the last 12 years. For this analysis, we have reviewed outcomes in those 61 patients managed exclusively by our multidisciplinary team (single center, single surgeon). Referral indications were as follows: indeterminate magnetic resonance imaging (MRI; n = 38, 62.3%), occult residual (n = 14, 23.0%), (radio-)surgical planning (n = 6, 9.8%), and occult de novo tumor (n = 3, 4.9%). RESULTS: A total of 33/61 patients (54.1%) underwent PET-guided surgery. Twenty-four of 33 patients (72.7%) achieved complete biochemical remission following (re-)surgery. Insulin-like growth factor 1 levels were reduced to <2 × upper limit of normal (ULN) in 6 of the remaining 9 cases, 3 of whom achieved levels of <1.1 × ULN compared with mean preoperative levels of 2.4 × ULN (SD 0.8) for n = 9. Only 3 patients developed single new hormonal deficits (gonadotropic/thyrotropic insufficiency). There were no neurovascular complications after surgery. CONCLUSION: In patients with persistent/recurrent acromegaly or occult tumors, Met-PET can facilitate further targeted intervention (surgery/radiosurgery). This led to complete remission in most cases (24/33) or significant improvement with comparatively low risk of complications. L-[methyl-11C]-methionine-positron emission tomography should therefore be considered in all patients who are potential candidates for further surgical intervention but present no clear target on MRI.

Efficacy of pasireotide LAR for acromegaly: a prolonged real-world monocentric study.

Background: Acromegaly is caused by excessive growth hormone (GH) and insulin-like growth factor 1 (IGF1). Medical therapy plays a role as a treatment option for persistent disease after non-curative surgery or as a first-line therapy when surgery is not feasible. Pasireotide-LAR (Pas-LAR) is recommended for patients with acromegaly as second-line treatment. Aim: To evaluate the patients characteristics predictive of an adequate response to Pas-LAR and the long-term efficacy and safety of the Pas-LAR treatment. Methods: Data from 19 patients with active acromegaly, who were and resistant or intolerant to first-line medical therapy and were switched to pas-LAR have been retrospectively collected. We compared the baseline clinical and biochemical characteristics of patients who were found to respond to Pas-LAR therapy (responders, n=14) with those of patients who did not respond (non-responders, n=5). We then evaluated the Pas-LAR efficacy and safety during long-term follow-up in responders. Results: IGF1 normalization occurred in 71.4% of responders after one injection. IGF1 levels, [median(interquartile range) of the upper limit of the normal range (ULN) fold increase] were higher in non-responders compared to responders within the initial month of therapy [1.40(1.30-2.34) vs 0.70(0.55-1.25), respectively, p=0.009] and after three [1.77(1.74-2.29) vs 0.94(0.82-1.13), respectively, p=0.029] and six months [1.68(1.33-1.72) vs 1.00(0.65 -1.28), respectively, p=0.002]. Out of 6 patients with symptomatic headache (all in responder group), 5 and 1 reported the resolution and improvement of headache, respectively, already after the first injection. Median HbA1c levels tended to increase from baseline to 6 months both in responder (36 mMol/Mol to 42 mMol/Mol) and non-responder patients (45 mMol/Mol to 48 mMol/Mol). During long term follow up, in the responder group 2 new patients developed diabetes. Tumor shrinkage was observed in 6 out of 7 evaluated responders, with no cases of size increase during the long-term follow-up. Conclusion: Pas-LAR is effective and safe and the early identification of responders is possible just after the first administration.

A Novel Preoperative Score to Predict Long-Term Biochemical Remission in Patients with Growth-Hormone Secreting Pituitary Adenomas.

OBJECTIVE: Transsphenoidal surgery (TSS) is considered the treatment of choice in most patients with growth hormone (GH)-secreting pituitary adenomas. Several preoperative factors have been studied to predict postsurgical remission. Our objective was to design a score that could be used in the preoperative setting to identify patients that will achieve long-term biochemical remission after TSS. METHODS: A retrospective analysis of consecutive patients with GH-secreting pituitary adenomas that underwent TSS in our institution from 2000 to 2015 who fulfilled prespecified criteria were included. Logistic regression methods were used to evaluate independent preoperative variables predicting long-term remission. Beta coefficients were used to create a scoring system for clinical practice. RESULTS: Sixty-eight patients were included, with a mean follow-up time of 87 months. Twenty (29%) patients had tumors with a Knosp grade ≥ 3A. Gross-total resection was achieved in 43 (63%) patients. Thirty-three (48%) patients had long-term biochemical remission after TSS. In a multivariate analysis, the following variables were statistically significantly associated with long-term biochemical remission: age, adenoma size (diameter), Knosp grade, GH level, and insulin growth-factor 1index 1 at diagnosis. A score of <3 out of 8 total points was identified as a cutoff associated with long-term remission, with a sensitivity of 91.4% and specificity of 72.7% (AUC 0.867, OR 28.44, 95% CI 6.94-116.47, P = < 0.001). CONCLUSIONS: A novel, simple, easy-to-use scoring system was created to identify patients with the highest chances of long-term biochemical remission following TSS. This scale should be prospectively validated in a multicenter study before widespread adoption.

Position statement on the diagnosis and management of acromegaly: The French National Diagnosis and Treatment Protocol (NDTP).

Acromegaly is a rare disease with prevalence of approximately 60 cases per million, slight female predominance and peak onset in adults in the fourth decade. Clinical diagnosis is often delayed by several years due to the slowly progressive onset of symptoms. There are multiple clinical criteria that define acromegaly: dysmorphic syndrome of insidious onset, symptoms related to the pituitary tumor (headaches, visual disorders), general signs (sweating, carpal tunnel syndrome, joint pain, etc.), complications of the disease (musculoskeletal, cardiovascular, pneumological, dental, metabolic comorbidities, thyroid nodules, colonic polyps, etc.) or sometimes clinical signs of associated prolactin hypersecretion (erectile dysfunction in men or cycle disorder in women) or concomitant mass-induced hypopituitarism (fatigue and other symptoms related to pituitary hormone deficiencies). Biological confirmation is based initially on elevated IGF-I and lack of GH suppression on oral glucose tolerance test or an elevated mean GH on repeated measurements. In confirmed cases, imaging by pituitary MRI identifies the causal tumor, to best determine management. In a minority of cases, acromegaly can be linked to a genetic predisposition, especially when it occurs at a young age or in a familial context. The first-line treatment is most often surgical removal of the somatotroph pituitary tumor, either immediately or after transient medical treatment. Medical treatments are most often proposed in patients not controlled by surgical removal. Conformal or stereotactic radiotherapy may be discussed on a case-by-case basis, especially in case of drug inefficacy or poor tolerance. Acromegaly should be managed by a multidisciplinary team, preferably within an expert center such as a reference or skill center for rare pituitary diseases.

Pituitary adenomas registry in Thailand.

PURPOSE: Pituitary adenomas are the most common sellar tumors, and may cause adverse outcomes in terms of morbidity and mortality if left untreated or if diagnosis is delayed. No data exists on the prevalence, characteristics, and prognosis of pituitary adenomas in Thailand. The systematic registration of clinical characteristics may improve patient care and prognosis for this disease in Thailand. METHODS: This was a retrospective study conducted in 11 academic referral centers. All patients diagnosed with pituitary adenomas during the 2011---2014 period were enrolled in the study. The information was correlated with two national databases. RESULTS: A total of 1,283 pituitary adenoma patients were identified. The adenomas were: non-functioning 50.1%, prolactinoma 29.4%, acromegaly 14.7%, Cushing disease 3.8%, gonadotropin-producing tumor 1.0%, TSH-secreting tumor 0.6%. The mean age was 49.2±15.2 years. Sixty-three percent of patients were female. Most common complaint was visual impairment (27.7%). The average size of the tumor was 22.2±16.1 mm. Fifty-nine percent of patients underwent surgery. Median follow-up was 27.4 months (0-24 years). After treatment, 72.4% improved, and 10.4% were cured. Overall results of treatment in non-functioning adenoma, prolactinoma (medically treated), acromegaly, Cushing, TSH, gonadotropin producing adenoma were: improved/cured in 81/5.5, 86/5.7, 55.9/30, 54.2/31.2, 85.7/14.3, 69.2/15.4% respectively. CONCLUSION: Pituitary adenomas in academic centers in Thailand were found predominantly in female in the 4th decade of life. After treatment 72.4% of patients improved and 10% had full recovery. A health promotion system aimed to improve patient and physician recognition and physician expertise may improve the prognosis of these diseases.

A pharmacophore screening approach of homeopathic phenols for a renovated design of fragment-optimized Bauhiniastatin-1 as a drug against acromegaly.

OBJECTIVE: Acromegaly is a fatal and chronic disease that is caused by the abnormal secretion of growth hormone (GH) by the pituitary adenoma or pituitary tumor, resulting in an increased circulated concentration of insulin-like growth factors 1 (IGF-1), where in most of the cases it is secreted by a pituitary tumor. Higher levels of GH cause an increase in IGF-1 in the liver leading to multiple conditions such as cardiovascular diseases, glucose imbalance, cancer, and sleep apnea. Medical treatments such as surgery and radiotherapy can be used as the first choice of patients; however, specified human growth hormone control should be an essential treatment strategy due to an incidence rate of 0.2-1.1 yearly. Therefore, the main focus of this study is to develop a novel drug for treating acromegaly by exploiting medicinal plants that have been screened using phenol as a pharmacophore model to identify target therapeutic medicinal plant phenols. MATERIALS AND METHODS: The screening identified thirty-four pharmacophore matches of medicinal plant phenols. These were selected as suitable ligands and were docked against the growth hormone receptor to calculate their binding affinity. The candidate with the highest screened score was fragment-optimized and subjected to absorption, distribution, metabolism, and excretion (ADME) analysis, in-depth toxicity predictions, interpretation of Lipinski's rule, and molecular dynamic simulations to check the behavior of the growth hormone with the fragment-optimized candidate. RESULTS: The highest docking energy was calculated as -6.5 K/mol for Bauhiniastatin-1. Enhancing the performance of Bauhiniastatin-1 against the growth hormone receptor with fragment optimization portrayed that human growth hormone inhibition can be executed in a more efficient and better way. Fragment-optimized Bauhiniastatin-1 (FOB) was predicted with high gastrointestinal absorption, a water solubility of -2.61 as soluble, and synthetic accessibility of 4.50, achieving Lipinski's rule of 5, with low organ toxicity prediction and interpreting a positive behavior against the targeted protein. The discovery of a de novo drug candidate was confirmed by the docking of fragment-optimized Bauhiniastatin-1 (FOB), which had an energy of -4,070 Kcal/mol. CONCLUSIONS: Although successful and completely harmless, present healthcare treatment does not always eradicate the disease in some individuals. Therefore, novel formulas or combinations of currently marketed medications and emergent phytochemicals will provide new possibilities for these instances.

Long-term Efficacy and Safety of Pasireotide in Patients With Acromegaly: 14 Years of Single-Center Real-World Experience.

CONTEXT: Acromegaly is a rare, chronic, debilitating disorder caused by prolonged hypersecretion of growth hormone (GH) and overproduction of insulin-like growth factor I (IGF-I). Medical therapies, including the somatostatin receptor ligand (SRL) pasireotide, are frequently used to restore biochemical control. OBJECTIVE: As patients often receive therapy over prolonged periods, long-term data from real-life settings are needed. METHODS: A retrospective analysis was performed using a prospectively maintained database of all patients with acromegaly from our primary care center who were enrolled in clinical studies with pasireotide (first visit November 2008). The main outcome measures were safety and biochemical control (age-adjusted IGF-I ≤ upper limit of normal). RESULTS: Patients (n = 50) entered 4 parental studies and 30 continued in the rollover; at data cutoff (June 2022), 27 were still receiving pasireotide. Overall, median (range) exposure was 58 (3-137) months. Normal IGF-I was achieved in 54%, and acromegaly symptoms and quality of life were improved with treatment. No predictors of pasireotide response were identified; however, controlled patients had smaller tumors and lower GH at baseline. Tumor volume reduction occurred in 63% of evaluable patients (n = 10/16). Most patients presented hyperglycemic events, including 63.2% of patients with normal glucose before treatment. Older patients and those with higher IGF-I, glucose, and HbA1c at baseline had higher glucose and HbA1c during pasireotide treatment. CONCLUSION: Pasireotide provided clinical benefit and was well tolerated for more than 11 years of treatment in acromegaly patients, most of whom were resistant to first-generation SRLs.

Multidisciplinary management of difficult/aggressive growth-hormone pituitary neuro-endocrine tumors.

Growth Hormone-secreting adenomas exhibits variable biological behavior and heterogeneous natural history, ranging from small adenomas and mild disease, to invasive and aggressive neoplasms with more severe clinical picture. Patients not cured or controlled after neurosurgical and first-generation somatostatin receptor ligands (SRL) therapy could require multiple surgical, medical and/or radiation treatments to achieve disease control. To date, no clinical, laboratory, histopathological, or neuroradiological markers are able to define the aggressiveness or predict the disease prognosis in patients with acromegaly. Therefore, the management of these patients requires careful evaluation of laboratory assessments, diagnostic criteria, neuroradiology examinations, and neurosurgical approaches to choose an effective and patient-tailored medical therapy. A multidisciplinary approach is particularly useful in difficult/aggressive acromegaly to schedule multimodal treatment, which includes radiation therapy, chemotherapy with temozolomide and other, recent emerging treatments. Herein, we describe the role of the different members of the multidisciplinary team according to our personal experience; a flow-chart for the therapeutic approach of difficult/aggressive acromegaly patients is proposed.

Modern approach to resistant acromegaly.

BACKGROUND: Targets of acromegaly treatment are normalization of biochemical values, removal/reduction/stabilization of the pituitary mass, control of clinical activity and mortality with a multimodal/multidisciplinary approach. Despite significant technological and pharmacological progress, still several patients with acromegaly bear a resistant somatotroph adenoma and active disease may persist for many years with resultant poor clinical outcomes. AIM: To review briefly definition and pathophysiology of resistance to acromegaly treatment and the options of medical treatment in this context, exploring the role of novel clinical and molecular biomarkers in the personalization of therapy and proposing updates to the currently available guidelines for the treatment of resistant GH-secreting adenomas. CONCLUSIONS: In the last few years, in parallel with the increased number of medical options available for the therapy of acromegaly, relevant advances occurred in the understanding of the role of novel molecular and clinical biomarkers in predicting the responsiveness to second-line medical treatments, such as Pegvisomant and Pasireotide LAR, and helping clinicians in the personalization of the follow-up and treatment of resistant somatotroph adenomas. The integration of these findings into the existing guidelines may represent a possibly important step forward in the management of "difficult" acromegaly patients.

Acromegaly with joint pain as an initial symptom: A case report.

BACKGROUND: Acromegaly is caused by the long-term excessive secretion of growth hormone (GH) and insulin-like growth factor-1 (IGF-1). It can cause excessive hyperplasia of bone, cartilage, and soft tissue. CASE PRESENTATION: A 50-year-old woman had a history of joint pain and swelling for more than 1 year. She visited a local primary care clinic, but her illness was not diagnosed by a primary care physician. After relevant examination in our hospital, we excluded inflammatory arthritis such as rheumatoid arthritis, immune disease-related arthritis, and infectious arthritis, and considered osteoarthritis or endocrine-metabolic arthritis. When we examined her again, we found that her fingers and toes were enlarged. She was diagnosed with acromegaly after IGF-1 test, and pituitary magnetic resonance imaging. Her joint symptoms were significantly relieved and her prognosis was good after surgery in another hospital. CONCLUSIONS: Acromegaly is a complex and rare disease, which is difficult to diagnose. When a patient presents with arthralgia, it is easily misdiagnosed as a rheumatic disease, and the diagnosis and treatment are delayed.

Predictors of postoperative biochemical remission in lower Knosp grade growth hormone-secreting pituitary adenomas: a large single center study.

PURPOSE: Growth hormone-secreting pituitary adenomas (GH-PAs) with a low Knosp grade are typically associated with a good postoperative biochemical remission (BR) rate. However, a proportion of patients do not achieve remission. In this study, we aimed to investigate predictive factors of postoperative remission for lower Knosp GH-PAs. METHODS: In this retrospective study, we enrolled 140 patients who were diagnosed with lower Knosp (0-2) GH-PAs and received trans-sphenoidal surgery between December 2016 and June 2021 from the largest pituitary tumor surgery center in southern China. The univariate, binary Logistic regression, and receiver operating characteristic curve (ROC) analyses were employed to determine independent predictors and cutoff values of remission. The postoperative outcome was defined as remission using the 2010 consensus criteria of acromegaly. RESULTS: One hundred and thirty six patients (97.1%) achieved gross total resection. The postoperative long-term BR was 68.6%. Empty sella, tumor maximum diameter and postoperative GH levels were independent factors predicting remission. ROC revealed that postoperative 24 h GH ≤ 1.3 ng/mL and ≤ 1.23 ng/mL were valuable predictors for 3-month and long-term remission respectively, and that postoperative 3-month GH ≤ 1.6 ng/mL and tumor maximum diameter ≤ 17 mm were predictors for delayed remission. CONCLUSION: Early postoperative GH levels can be used as predictors of remission. However, BR was not associated with preoperative somatostatin analogs therapy or Knosp grade (0-2). For patients without residual tumor or recurrence and whose GH levels are slightly elevated within 1 year after surgery, adjuvant treatments may not be necessary.

Endoscopic endonasal transsphenoidal surgery in acromegaly with conchal sphenoid sinus.

BACKGROUND: A conchal non-pneumatized sphenoid sinus tends to be considered as unfavorable for transsphenoidal surgery because of procedural difficulties. Especially in acromegalic patients, the proportion of the conchal type of sphenoid sinus is potentially high compared with that of other patients who have a pituitary tumor. This report investigates the characteristics and surgery of the conchal type of sphenoid sinus in acromegaly along with the internal bone properties. CLINICAL PRESENTATION: A 70-year-old man with acromegaly underwent endoscopic endonasal transsphenoidal surgery. Intraoperatively, the anterior wall of the non-pneumatized sphenoid was cortical, however, the cancellous bone was very soft, included fatty tissue, and was easily removed by suction. The sellar lesion could be reached without any problems, and finally, total tumor resection was achieved. CONCLUSION: Based on this surgical case, the conchal sphenoid sinus of acromegaly is not always homogeneous solid bone but may contain soft fatty tissue. Therefore, although the sphenoidal characteristics may have an impact on the surgical procedures, precise assessment pre- and intraoperatively can make transsphenoidal surgery with conchal sphenoid sinus feasible.

Giant growth hormone-secreting pituitary adenomas from the endocrinologist's perspective.

OBJECTIVES: Since giant (≥40 mm) GH-secreting pituitary adenomas are rarely encountered, data on their characteristics and treatment outcomes are limited. We aimed to investigate the characteristics of giant GH-secreting pituitary adenomas and to compare their clinical, biochemical, imaging and histopathological features with non-giant macroadenomas. MATERIALS AND METHODS: We have evaluated 15 (six female/nine male) and 57 (29 female/28 male) patients with acromegaly in giant and <40 mm adenoma groups, respectively. Patients with <40 mm adenoma were further divided into subgroups with adenoma size 20-29 mm and 30-39 mm. RESULTS: In giant adenoma group, median (IQR) preoperative maximal diameter of adenoma was 40 mm (5 mm), median preoperative GH level was 40 (153.4) ng/mL and median baseline IGF-1 level was 2.19 (1.88) × ULN for age and sex. The number of surgeries was significantly higher in giant adenoma group (median 2, IQR 2) in which 66.7% of patients underwent repeated surgeries (p = 0.014). Residual tumor was detected after last operation in all patients with giant adenoma. Total number of treatment modalities administered postoperatively increased as adenoma size increased (p = 0.043). After a median follow-up duration of 10 years (IQR 10), hormonal remission was achieved in six patients (40%) of giant adenoma group, while the rate of hormonal remission in non-giant adenoma group was 37%. Although preoperative GH and IGF-1 levels and Ki-67 index tended to be higher with increasing adenoma size, there was no statistically significant difference between groups in terms of these variables, as well as age, sex and invasion status. CONCLUSION: Hormonal remission rates of acromegaly patients with ≥20 mm pituitary macroadenoma were comparable. However, giant GH-secreting pituitary adenomas require an aggressive multimodal treatment approach.

Gigantism: microsurgical treatment by transsphenoidal approach and prognostic factors.

PURPOSE: We present the results of transsphenoidal microsurgical treatment in 14 patients with gigantism. The influence on the prognosis of factors such as the tumor size and preoperative levels of GH and IGF-1 is also quantified. MATERIALS AND METHODS: The patients, operated between 1982 and 2004, were reviewed retrospectively in June 2022. All patients had complete endocrinological studies in the preoperative period and a postoperative control between 6 days and 3 weeks. Follow-up has been supported with annual check-ups between 3 and 31 years. We have compared the preoperative levels of GH and IGF-1 of these patients with the levels of a series of acromegalic patients operated on in the same Center. RESULTS: In this series there were 4 women and 10 men. The age ranged between 14 and 21 years. In 6 patients, postoperative hormone levels achieved the disease control criteria (42.8%). The CT/MRI studies revealed the existence of invasive tumors in 10 of the patients (71.4%). Postoperative CT/MRI showed no tumor tissue in 3 patients but in 7 patients there were tumor remains. The remaining 4 patients had abnormal images although not considered as tumor. A statistical comparison of preoperative serum GH and IGF-1 levels in patients with gigantism and patients with acromegaly showed a significant elevation in the former. CONCLUSION: Pituitary adenomas that cause gigantism are generally large and invasive, which makes them difficult to cure. High preoperative levels of GH and IGF-1 are also factors that decrease remission.

Acromegaly among a Moroccan population.

Acromegaly is defined as an acquired dysmorphytic syndrome due to excessive secretion of growth hormone (GH) and consequently of insulin-like growth factor-1 (IGF-1). This is a retrospective study of patients who were hospitalized in the Endocrinology Department of the Mohammed V Military Academic Hospital in Rabat over a period of 14 years (2008 to 2022), reporting on their clinical, paraclinical and evolutionary profiles and comparing the results with the data in the literature. Nineteen patients were included in our study. The mean age was 42.7 ± 11.6 years, with a male predominance. The clinical manifestations were dominated by a dysmorphic syndrome present in 97.4% of cases, followed by complications related to acromegaly in 88.9% of cases. The diagnosis was made when GH and IGF-1 values were elevated in 88.9% and 93.8% of cases, respectively; with a mean GH value of 25.1 µg/L. Magnetic resonance imaging (MRI) was used to diagnose the location of pituitary adenoma in all cases, 78.9% of which were macroadenomas and 21.1% microadenomas. The majority of patients (78.9%) had recourse to transsphenoidal surgery. Medical treatment was carried out in 89.5% of cases. Postoperative radiotherapy was performed in 33% of cases. Disease control was achieved in 30.1% of cases. This study shows the complex management of acromegaly. Disease control is a necessary condition in order to avoid complications, but is often difficult to obtain.

Acromegaly: pathogenesis, diagnosis, and management.

Growth hormone-secreting pituitary adenomas that cause acromegaly arise as monoclonal expansions of differentiated somatotroph cells and are usually sporadic. They are almost invariably benign, yet they can be locally invasive and show progressive growth despite treatment. Persistent excess of both growth hormone and its target hormone insulin-like growth factor 1 (IGF-1) results in a wide array of cardiovascular, respiratory, metabolic, musculoskeletal, neurological, and neoplastic comorbidities that might not be reversible with disease control. Normalisation of IGF-1 and growth hormone are the primary therapeutic aims; additional treatment goals include tumour shrinkage, relieving symptoms, managing complications, reducing excess morbidity, and improving quality of life. A multimodal approach with surgery, medical therapy, and (more rarely) radiation therapy is required to achieve these goals. In this Review, we examine the epidemiology, pathogenesis, diagnosis, complications, and treatment of acromegaly, with an emphasis on the importance of tailoring management strategies to each patient to optimise outcomes.

Age, GH/IGF-1 levels, tumor volume, T2 hypointensity, and tumor subtype rather than proliferation and invasion are all reliable predictors of biochemical response to somatostatin analogue therapy in patients with acromegaly: A clinicopathological study.

PURPOSE: To determine whether biochemical responses to long-acting forms of first-generation somatostatin analogue (SSA) therapy in patients with acromegaly could be predicted from baseline and postoperative hormone concentrations, and tumor radiological and histopathological characteristics. METHODS: A total of 68 patients with acromegaly for whom postoperative SSA therapy was started were categorized according to their responses to treatment (SSA-responders vs. non-responders). The patients were compared based on their demographic characteristics, hormone levels, magnetic resonance imaging (MRI), and histopathological findings. Receiver-operating-characteristic (ROC) curves were constructed using the predictive factors that were significant in the univariate analysis to determinate the optimal cut-off values. RESULTS: The SSA-responders were significantly older (p = 0.041). Lower GH at diagnosis (p = 0.036), the postoperative 1st-week GH level (p = 0.027), baseline GH, insulin-like growth factor-1 (IGF-1) and IGF-1% upper limit of normal (ULN) (p = 0.001, p = 0.006, p = 0.023, respectively) were associated with biochemical response. T2-hypointensity and lower tumor volume were more common in the SSA-responders (p = 0.018, p = 0.03, respectively). Compared to sparsely granulated somatotroph tumors, densely granulated somatotroph tumors and other PitNETs causing GH excess including mammosomatotroph and mixed somatotroph and lactotroph tumors were more likely to respond to SSA therapy (p = 0.026, p = 0.03, respectively). The cut-off values generated by ROC curve analysis were GH at diagnosis of ≤8.8 ng/mL, GH at baseline of ≤2.69 ng/mL, IGF-1 at baseline ≤461.5 ng/mL, IGF-1% ULN at baseline ≤180.4%, and tumor volume of ≤1.11 cm3 (all p < 0.05). There were no differences between the groups in terms of tumor invasiveness, proliferative activity (mitotic count per 2 mm2 and Ki-67 labeling index) and quantitative analyses of T2-weighted MRI. CONCLUSION: This study underscores that advanced age, low baseline GH and IGF-1 at diagnosis, low tumor volume, densely granulated tumor subtype, and T2 hypointensity may help predict biochemical response to SSA therapy in cases of acromegaly. These variables should be assessed with utmost attention for all patients prior to SSA treatment. In cases of possible resistance to SSA therapy, therapeutic activity should be monitored more closely and other therapies should be administered immediately in the event of poor response.