What is the recommended treatment for a patient presenting with a low-grade serous tumor?

Low-Grade Serous Ovarian Cancer: Incidence, Presentation, and Treatment

Incidence and Epidemiology

Low-grade serous carcinoma accounts for approximately 5-10% of all serous ovarian cancers and represents a biologically distinct entity from high-grade serous carcinoma. 1, 2

• These tumors typically present in younger women (median age 40-50 years) compared to high-grade disease 1, 2
• They are classified as Type I ovarian cancers, characterized by slow growth and relative chemoresistance 2
• KRAS mutations occur in 20-40% of cases, while BRAF mutations are rare (approximately 5%) 1, 2
• TP53 mutations are uncommon, unlike high-grade serous carcinomas 2

Clinical Presentation

• Patients often present with more advanced stage disease (stage III-IV) despite the indolent nature 3
• The majority of tumors express high levels of estrogen receptor (ER) and progesterone receptor (PR) 3
• Despite advanced presentation, overall survival is prolonged compared to high-grade disease due to the slower biological behavior 1, 2

Treatment Approach

Primary Surgical Management

Primary debulking surgery with complete cytoreduction (no macroscopic residual disease) is the single most critical intervention due to the inherent chemoresistance of low-grade serous carcinoma. 3

• All patients must be evaluated by a fellowship-trained gynecologic oncologist before initiating any treatment 3, 4
• Complete surgical staging includes bilateral salpingo-oophorectomy, hysterectomy, omentectomy, peritoneal biopsies, and lymph node assessment 3, 4
• Even cytoreduction to residual disease <1 cm may improve survival when complete resection is not feasible, though this is a weaker recommendation 3
• Fertility-sparing surgery (unilateral salpingo-oophorectomy with comprehensive staging) may be considered for select patients with unilateral stage IA disease 3, 4

Adjuvant Chemotherapy

Despite limited chemosensitivity, carboplatin plus paclitaxel for 6 cycles remains the standard adjuvant chemotherapy. 3

Stage-Specific Chemotherapy Recommendations:

• Stage IA/IB: Observation is appropriate 3
• Stage IC-II: Carboplatin/paclitaxel for 3-6 cycles, or observation (category 2B alternative) 3
• Stage III-IV: Carboplatin/paclitaxel for 6 cycles 3

Addition of bevacizumab to carboplatin/paclitaxel should be considered based on retrospective data showing activity in low-grade disease. 3

Hormonal Maintenance Therapy

Maintenance antiestrogen therapy (aromatase inhibitors such as anastrozole or letrozole, or tamoxifen) should be considered after completion of chemotherapy given the high ER/PR expression. 3, 4

• This is a category 2B recommendation with level IV evidence, but represents an important option given the hormonal sensitivity of these tumors 3
• Small retrospective studies suggest therapeutic value in both first-line and recurrent settings 3

Recurrent Disease Management

Secondary cytoreductive surgery should be pursued with the goal of complete resection (no macroscopic residual disease) in appropriately selected patients with recurrent disease. 3

• Significantly improved progression-free survival (PFS) and overall survival (OS) have been demonstrated with complete secondary cytoreduction 3
• Treatment options for unresectable recurrence include:
  • Salvage chemotherapy (carboplatin-based regimens) 1
  • Hormonal therapy (aromatase inhibitors, tamoxifen, or leuprolide) 3, 1
  • MEK inhibitors (trametinib) have shown activity, particularly in KRAS-mutated disease 5, 6

Critical Pitfalls to Avoid

Do not treat low-grade serous carcinoma identically to high-grade disease—they are molecularly and clinically distinct entities with different treatment sensitivities. 4, 7

• Do not rely solely on chemotherapy; maximal surgical cytoreduction is paramount given the relative chemoresistance 3
• Do not proceed with neoadjuvant chemotherapy without gynecologic oncologist evaluation, as these patients may be better served with primary surgery 4, 7
• Do not omit consideration of hormonal therapy, as the high ER/PR expression makes this a rational and well-tolerated option 3, 4
• Do not expect response rates comparable to high-grade disease; multiple retrospective studies confirm lower chemotherapy response rates (20-30% vs 70-80%) 3

Emerging Therapies

• MEK inhibitors (trametinib, binimetinib) have demonstrated activity in recurrent disease, with particular benefit in KRAS-mutated tumors 5, 6
• CDK 4/6 inhibitors and PI3KCA inhibitors are under investigation 5
• A phase III trial of MEK inhibitor versus chemotherapy in platinum-resistant disease was closed for futility, tempering initial enthusiasm 3