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Surgical Oncology Board Exam Preparation — ABS-CGSO (USA)

The American Board of Surgery Complex General Surgical Oncology (CGSO) qualifying and certifying examinations demand mastery across every solid-organ malignancy. Practise with thousands of CGSO-mapped clinical vignettes written by practising surgical oncologists, each answer referenced to NCCN, AJCC 8th Edition and the landmark trials examiners expect you to know.

Content reviewed 26 August 2026 against current guidelines.

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Exam format

Format
Qualifying Exam (~200 MCQ, computer-based) + virtual oral Certifying Exam
Duration
QE ~5 h (three 90-min sessions); CE four 30-min sessions
Frequency
Each exam offered once per academic year
Pass rate
Criterion-referenced; not publicly specified
Exam fee
See the American Board of Surgery (absurgery.org)

Eligibility requirements

  • Current certification or eligible for certification by the American Board of Surgery (ABS)
  • Completion of an ACGME-accredited or equivalent fellowship in surgical oncology (minimum 1 year)
  • Active surgical practice including oncologic cases
  • Maintenance of Certification (MOC) participation if previously certified

Syllabus breakdown

Breast Oncology20%
Melanoma & Skin Cancer15%
Soft Tissue Sarcoma & Retroperitoneal Sarcoma15%
Colorectal & Anal Cancer15%
Hepatopancreatobiliary Oncology15%
Peritoneal Malignancy, Gastric & Upper GI10%
Endocrine Oncology10%

A real ABS-CGSO question

Taken from the bank, not written for this page. Answer it in your head, then open the explanation.

A 70-year-old woman with multiple comorbidities (diabetes, moderate CKD stage 3b, ECOG PS 2) is diagnosed with a 20 mm, grade 2, ER-positive, HER2-negative invasive carcinoma. She has clinically node-negative disease. She strongly wishes to avoid chemotherapy. Oncotype DX is requested and returns RS 8. According to NCCN 2025, TAILORx data, and geriatric oncology principles, what is the most appropriate recommendation?

  1. AChemotherapy plus endocrine therapy, as all node-negative patients should be counselled on chemotherapy
  2. BNo systemic therapy; surgery plus radiotherapy is sufficient for grade 2 ER-positive tumours in the elderly
  3. CEndocrine therapy alone (aromatase inhibitor); RS ≤10 indicates negligible chemotherapy benefit
  4. DWait for MammaPrint result to supplement Oncotype DX before deciding
  5. EEndocrine therapy alone but with tamoxifen, as AIs are contraindicated in elderly women with CKD
Show the answer and explanation

Correct answer: C

TAILORx (Sparano et al., NEJM 2018) showed that in patients with RS 0–10, endocrine therapy alone was non-inferior to chemoendocrine therapy in node-negative HR-positive, HER2-negative breast cancer. The 9-year distant recurrence rate in the RS 0–10 group was 3%, with no chemotherapy benefit across all age subgroups including younger women. For this 70-year-old with RS 8, chemotherapy adds no proven benefit and would carry significant risk given her ECOG PS 2, CKD, and diabetes. Aromatase inhibitors are the preferred endocrine therapy for postmenopausal women — CKD stage 3b is not a contraindication to AIs (dose adjustment not required; AIs are hepatically metabolised and minimally renally excreted). Tamoxifen increases thromboembolic risk. Withholding all systemic therapy would undertreat her — endocrine therapy reduces recurrence by approximately 40% in RS ≤10 disease. MammaPrint adds no clinical utility when Oncotype DX RS is already available and clearly in the low-risk range.

Teaching point. RS ≤10 (TAILORx): endocrine therapy alone, no chemotherapy regardless of age or comorbidity. AIs are safe in CKD — hepatic metabolism, no renal dose adjustment.

Referenced to NCCN Breast Cancer 2025; TAILORx (Sparano, NEJM 2018)

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Preparation tips

  • Focus your first weeks on the highest-weight syllabus areas — they account for over half the marks and offer the fastest return on study time.
  • Use active recall with timed question sessions rather than passive re-reading: the ABS-CGSO multiple-choice paper rewards speed and precision under pressure.
  • Cross-reference every explanation with the guideline section it cites. Over a 3–6 month cycle that builds the mental index the 2-station oral demands, where you have to justify a decision rather than recognise it.

How these questions are validated

Every question is written by Pablo Lozano Lominchar, MD, PhD, and mapped to this board’s published syllabus. Before it enters the bank it has to pass an automated check: five options, a written explanation, and a citation — a named society guideline or a named trial. Benign and functional topics cannot be published without a society guideline; oncological ones cite NCCN, ESMO or AJCC, and the classification systems that govern a topic — Bethesda, TIRADS, Atlanta, Prague, Chicago — have to appear where they apply. The author has audited the full active bank against current guideline versions: what fails is re-cited, rewritten or withdrawn. 650 questions are currently withdrawn and are served to nobody.

Frequently asked questions

How do I prepare for the ABS Complex General Surgical Oncology exam?

The most efficient preparation combines high-volume, board-style question practice with guideline cross-referencing. Focus first on the highest-yield tumour sites (GI, breast, endocrine, HPB, sarcoma, melanoma), practise timed multiple-choice sessions to build recall speed, and confirm every answer against the cited NCCN or AJCC reference so the reasoning transfers to the certifying exam.

How many practice questions are available for the CGSO exam?

SurgBoardsQ&A provides more than 7,400 Complex General Surgical Oncology practice questions covering the full ABS CGSO content outline, each with a detailed explanation and guideline citation.

What topics are on the Complex General Surgical Oncology exam?

The CGSO exam spans gastrointestinal oncology, breast, endocrine (thyroid, parathyroid, adrenal), hepatopancreatobiliary tumours, soft-tissue sarcoma, melanoma and skin cancer, peritoneal surface malignancy, and the principles of staging, surgical margins and multidisciplinary decision-making.

Is there a free way to practise for the CGSO boards?

Yes. You can start with 50 free CGSO practice questions on SurgBoardsQ&A with no credit card required, then upgrade for unlimited access to the full bank.

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