Adrenocortical Carcinoma: A Rare Adrenal Tumor

Adrenocortical carcinoma (ACC) is a rare and aggressive cancer that originates in the adrenal cortex. This adrenal tumor often presents diagnostic challenges due to its nonspecific symptoms. Understanding its pathophysiology, clinical features, and management is crucial for improving outcomes. With an incidence of approximately 0.5–2 per million per year, adrenocortical carcinoma is considered a rare malignancy, yet it accounts for a significant proportion of adrenal incidentalomas that prove malignant.

The adrenal glands, located above each kidney, produce essential hormones including cortisol, aldosterone, and androgens. When cells in the adrenal cortex undergo malignant transformation, they can form an adenoma or carcinoma. Adrenocortical carcinoma is distinct from other adrenal tumors in its potential to secrete excess hormones and its propensity for local invasion and metastasis. Early detection is challenging because symptoms often appear late, and many tumors are discovered incidentally during imaging for unrelated conditions.

Understanding Adrenocortical Carcinoma

Adrenocortical carcinoma arises from the adrenal cortex and can be functional (hormone-secreting) or nonfunctional. Functional tumors produce cortisol, aldosterone, androgens, or a combination, leading to syndromes such as Cushing syndrome, hyperaldosteronism, or virilization. Nonfunctional tumors may grow silently until they cause mass effects or are discovered incidentally. The molecular pathogenesis involves alterations in the TP53, CTNNB1, and IGF2 genes, among others. Germline mutations in TP53 are associated with Li-Fraumeni syndrome, which increases the risk of adrenocortical carcinoma.

Risk factors for this adrenal tumor include genetic syndromes, such as Beckwith-Wiedemann syndrome, and possibly smoking and environmental exposures. However, most cases are sporadic. The median age at diagnosis is 40–50 years, but it can occur in children and older adults. The tumor is often large at presentation, with a mean diameter of 10–15 cm, and may invade adjacent structures like the kidney, diaphragm, or vena cava.

• Common symptoms: Abdominal pain, weight loss, weakness, early satiety, and palpable mass.
• Hormonal symptoms: Rapid onset of obesity, hypertension, diabetes, hirsutism, and menstrual irregularities.
• Incidental findings: Many adrenocortical carcinomas are found on CT or MRI performed for other reasons.

Diagnosis and Treatment of Adrenal Carcinoma

Diagnosis of adrenocortical carcinoma begins with imaging studies. Contrast-enhanced CT or MRI reveals a heterogeneous mass with irregular borders, necrosis, and delayed washout. 18F-FDG PET/CT can help differentiate benign from malignant adrenal tumors, as adrenocortical carcinoma typically shows high metabolic activity. Hormonal evaluation is essential to detect hypersecretion: measurement of cortisol, aldosterone, renin, androgens, and catecholamines to rule out pheochromocytoma.

Biopsy of adrenal masses is generally avoided due to the risk of bleeding and seeding, and it is reserved for cases where diagnosis is uncertain. Histopathology confirms adrenocortical carcinoma based on the Weiss score, which includes nuclear grade, mitotic rate, necrosis, and invasion. Immunohistochemistry for markers like inhibin, melan-A, and SF-1 aids in differentiation. Genetic testing for germline mutations is recommended for patients under 40 with family history of cancer.

Staging of adrenocortical carcinoma follows the ENSAT (European Network for the Study of Adrenal Tumors) classification, which considers tumor size, lymph node involvement, and distant metastases. Stage I (T1N0M0) has the best prognosis, while stage IV carries a poor outlook. Surgical resection is the mainstay for localized disease, ideally performed by an experienced surgeon via open approach, as laparoscopic resection may increase recurrence. Complete resection with negative margins (R0) is critical.

Adjuvant therapy with mitotane, an adrenolytic agent, is recommended for patients with high risk of recurrence (e.g., large tumor, high mitotic rate, incomplete resection). Mitotane suppresses cortisol synthesis and has cytotoxic effects on adrenal cells. However, its use is limited by side effects including gastrointestinal disturbances, neurological toxicity, and adrenal insufficiency. Radiation therapy may be used for local control of unresectable disease or palliation of bone metastases.

For advanced or metastatic adrenocortical carcinoma, systemic chemotherapy with etoposide, doxorubicin, and cisplatin (EDP) combined with mitotane is the standard first-line regimen. Second-line options include gemcitabine, paclitaxel, and targeted therapies such as sunitinib or everolimus in clinical trials. Immunotherapy has shown limited efficacy in adrenocortical carcinoma due to low tumor mutation burden. Novel agents targeting IGF-1R or FGFR are under investigation.

Prognosis and Follow-Up

The prognosis of adrenocortical carcinoma depends on stage at diagnosis, completeness of resection, and tumor biology. Recurrence rates are high, even after R0 resection, with 5-year disease-free survival around 60% for stage I–II and only 20% for stage III. Regular follow-up with imaging (CT or MRI every 3–6 months for the first 2 years, then annually) and hormonal markers is essential. Plasma chromogranin A and urinary steroid profiles can help detect recurrence early.

Management of recurrent disease includes repeat surgery if localized, mitotane therapy, and systemic chemotherapy. Palliative care plays a crucial role in symptom control and quality of life. Ongoing research into the molecular drivers of adrenocortical carcinoma offers hope for more targeted therapies in the future. Patient support groups and multidisciplinary care are vital for navigating this challenging diagnosis.

In conclusion, adrenocortical carcinoma is a rare but formidable adrenal tumor that requires prompt recognition and aggressive treatment. Advances in imaging, surgery, and medical therapy have improved outcomes, but early detection remains the most important factor. Increased awareness among clinicians and the public can lead to earlier diagnosis and better survival for patients with this rare cancer.