Open Adrenalectomy

Although laparoscopic surgery has become the treatment of choice for the majority of incidentally detected adrenal masses, and robotic approaches have been developed that appear to yield comparable results, ^[1] open adrenalectomy still plays an important role in the armamentarium of adrenal surgeons. ^{[2, 3]}

Adrenal surgery has a long history, with the first planned adrenalectomy performed in 1914 by Sargent. ^[4] Mayo performed the first flank approach for pheochromocytoma in 1927, though at the time of surgery, he was unaware of the full disease process involved. Through the early to mid-1900s, multiple changes in surgical approaches to the adrenal (suprarenal) gland were developed to augment several posterior and anterior approaches. For decades, little change to adrenal surgery was seen, until the first laparoscopic adrenalectomy was described by Gagner in 1992. ^[5]

Increasing use of imaging technologies, such as computed tomography (CT) and magnetic resonance imaging (MRI), for aid in diagnosis of other conditions has led to increased diagnosis of adrenal masses.

The incidence of these incidentally noted adrenal masses has been estimated to be around 5%. ^{[6, 7, 8, 4, 9]} Autopsy studies have supported this estimation, showing the incidence of adrenal masses found at autopsy also to be in the range of 3-5%. ^{[7, 4, 10]} Furthermore, studies of hospital discharges showed a 43.4% increase in adrenalectomy rates from 1988 to 2000. ^{[9, 11]} With increasing diagnosis and treatment of adrenal masses, optimization of cure and minimization of morbidity become particularly important.

Indications for adrenalectomy may seem straightforward at first. However, with the increasing rates of diagnosis of asymptomatic and likely benign adrenal masses, disagreements regarding optimal management remain. ^[12]

Masses larger than 6 cm have a rate of adrenocortical carcinoma of 25% and should be managed surgically. ^[10]  Masses smaller than 4 cm may be safely observed because their rate of adrenocortical carcinoma is 2%.

Size categories, however, do not alter management for hormonally active lesions; these should also be managed with surgical excision in most cases. The adrenal gland can be a common site for metastases, and thus, patients with known primary malignancies should be managed according to guidelines for the primary malignancy by stage and grade. For example, the adrenal gland is a common site for synchronous or metachronous metastasis from renal cell carcinoma; surgical excision can frequently offer primary cure in conjunction with nephrectomy. ^[13]

Surgical excision is indicated for the following adrenal pathologies:

• Conn syndrome
• Cushing syndrome
• Pheochromocytoma
• Large myelolipoma
• Metastatic tumors
• Adrenocortical carcinoma ^[14]
• Neuroblastoma (pediatric population)

The choice of approach will depend on the size and location of the mass, the possibility of malignancy, and the surgeon's experience with the different techniques. The open approach to adrenalectomy has been considered the gold standard for masses suspected of being adrenal carcinoma, ^{[15, 4, 16]}  though minimally invasive approaches may have a role to play in selected patients who are treated by experienced surgeons in high-volume institutions. ^{[17, 18]}

In addition, open adrenalectomy is the treatment of choice for patients in whom laparoscopic surgery is contraindicated. A patient's inability to undergo pneumoperitoneum is an absolute contraindication for laparoscopy. Multiple previous abdominal operations and obesity remain relative contraindications for laparoscopy.

Absolute contraindications for adrenal surgery of any sort include the following:

• Uncorrected coagulopathy
• Poor cardiac or pulmonary function

In cases of widely metastatic disease with a concomitant adrenal mass, tissue diagnosis should be obtained before the decision is made to proceed with adrenalectomy because primary adrenal carcinoma is rare.

Anatomy

The adrenal glands are paired glands superior to the kidneys bilaterally (see the image below) that reside within a separated layer of Gerota fascia, and they provide multiple functions in the body. (See the image below.)

The outer layer (cortex) of the gland contributes to homeostasis via its endocrine function, whereby it secretes cortisol, aldosterone, and dehydroepiandrosterone (DHEA). These hormones play pivotal roles in regulating salt and water balance and, in the case of DHEA, add virilization hormones to the hormonal milieu. The inner layer (adrenal medulla) is derived from neural crest cells and is important in the sympathetic regulation of the body by secreting norepinephrine. Several disorders of adrenal metabolism are known to involve hypersecretion of these different molecules.

For more information about the relevant anatomy, see Suprarenal (Adrenal) Gland Anatomy.

Procedural planning

Before operative intervention, treatment for appropriate coagulopathies and for hormonal excess should be instituted. Serum potassium levels should be corrected in hyperaldosteronism, and hypertension control should be initiated.

If cortisol excess is severe, inhibition of cortisol with ketoconazole, mitotane, or metyrapone should be considered. In addition, good glucose control is necessary, and operative replacement of steroids is indicated; the hypothalamic-pituitary-adrenal axis for the normal contralateral adrenal gland will remain suppressed for some time after removal of the abnormal adrenal tissue.

For pheochromocytoma, initiation of alpha blockade with either phenoxybenzamine or prazosin is an absolute necessity to protect the patient from the sympathetic surges possible with manipulation of the mass during surgery. For the same purpose, some authors have advocated preoperative use of calcium-channel blockers. In addition, vascular volume reexpansion is often necessary because of volume contraction with hypersympathetic states.

The outcomes of open adrenalectomy vary with the pathology of the disease process, and morbidity changes according to the approach chosen. Approaches that limit access to the peritoneum greatly decrease the rates of postoperative ileus; however, vascular control is often difficult.

The posterior lumbodorsal approach is also associated with high rates of neuromuscular morbidity, including chronic pain (14%), laxity in flank muscles (30%), and flank numbness (10%). ^[19]

With adrenalectomy alone, roughly 35% of patients with hyperaldosteronism no longer require medications for hypertension. ^[20]

Outcomes of adrenalectomy for adrenocortical carcinoma are generally poor because this disease tends to present at an advanced stage. A large retrospective review from MD Anderson Cancer Center reported an overall survival of around 58%, with 86% of these cases undergoing adrenalectomy. ^[21]

Other reports cited a 5-year survival rate in the area of 33%. ^[21]  When stratified for stage, 5-year survival was 20-45% for stage I adrenal tumors, 12.5-57% for stage II adrenal tumors, 5-18% for stage III adrenal tumors, and 0% for stage IV adrenal tumors. ^[22]  The most significant predictors of outcome after adrenalectomy for carcinoma are stage at presentation and complete resection. ^[23]

Autorino et al, in a systematic literature review and meta-analysis comprising nine retrospective case-control studies, compared open adrenalectomy (n = 557) and laparoscopic adrenalectomy (n = 240) with respect to surgical and oncologic outcomes in patients with adrenocortical carcinoma. ^[24]  The laparoscopic procedure was associated with a shorter duration of hospitalization and a higher incidence of peritoneal carcinomatosis, but no significant differences were found in overall recurrence rate, time to recurrence, or cancer-specific mortality.

Kastelan et al compared the long-term outcomes of open versus laparoscopic adrenalectomy in 46 patients with localized adrenocortical carcinoma without invasion of extra-adrenal tissues; the main outcomes analyzed were recurrence-free survival (RFS) and overall survival (OS). ^[25]  No differences in RFS and OS were found between the two groups. However, these results were derived from referral centers with substantial experience in managing adrenocortical carcinoma and thus may not necessarily be applicable to less specialized centers.

In a meta-analysis of 15 studies comparing minimally invasive adrenalectomy with open adrenalectomy in 2207 patients with adrenocortical carcinoma, Hu et al found the two approaches to be comparable in terms of operating time, postoperative complications, overall recurrence, and local recurrence. ^[26]  Minimally invasive adrenalectomy was associated with significant reductions in blood loss and length of stay but also with a greater likelihood of earlier recurrence, positive surgical margin, and peritoneal recurrence. The two approaches did not differ with respect to overall survival, cancer-specific survival, or recurrence/disease-free survival.

Outcomes for benign lesions, including hormone-secreting lesions, are excellent. Resolution of symptoms is achieved in nearly all patients, except those who have contralateral disease or sites of metastasis (in the case of pheochromocytoma).