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Chapter 8: Carcinoma of Unknown Primary

David R. Spigel; F. Anthony Greco

INTRODUCTION

Epidemiology

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Epidemiology
Incidence: Unknown✫ (Estimated at 30,000–45,000 patients/year) Stage at Presentation
Median age: Varies by histology (usually sixth decade) Local/regional: <10%
Male to female ratio: M ≅ F ≥2 sites: >90%

✫Due to patient heterogeneity and tumor registry misclassification

 

American Cancer Society. Cancer Facts & Figures 2013 Greco FA, Hainsworth JD. In: DeVita VT Jr et al, editors. Cancer: Principles & Practice of Oncology, 10th ed. Philadelphia: Wolters Kluwer; 2015:1720–1737

Hainsworth JD et al. J Clin Oncol 1991;9:1931–1938

Hainsworth JD, Greco FA. N Engl J Med 1993;329:257–263

Pathology

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Pathology
Adenocarcinoma (well differentiated or moderately differentiated) 60%
Poorly differentiated carcinoma/(± features of adenocarcinoma) 29%
Poorly differentiated malignant neoplasm 5%
Squamous carcinoma 5%
Neuroendocrine carcinoma 1%

Greco FA, Hainsworth JD. In: DeVita VT Jr et al, editors. Cancer: Principles & Practice of Oncology, 10th ed. Philadelphia: Wolters Kluwer; 2015:1720–1737Hainsworth JD, Greco FA. N Engl J Med 1993;329:257–263

Work-up

Clinical evaluation

  • H&P, including pelvic, breast, and rectal exams

  • CBC

  • Comprehensive metabolic profile

  • Urinalysis

  • Occult blood in feces

  • Lactate dehydrogenase (LDH)

  • Serum human chorionic gonadotropin (HCG)

  • Alpha-fetoprotein (AFP)

  • Carcinoembryonic antigen (CEA)

  • CA 19-9, CA 27–29 (or CA 15-3), CA 125; PSA (men)

  • Chest/abdominal/pelvic CT; mammograms (women)

Where appropriate:

  • Positron emission tomography (PET)

  • Bronchoscopy, and panendoscopy (particularly for squamous carcinomas neck)

Pathologic studies

  • Core needle or excisional biopsy preferred over fine-needle aspiration (FNA)/cytology (consider rebiopsy if insufficient material from initial biopsy)

  • Immunohistochemistry (IHC) analyses for:

    • CK7

      CK20

    • TTF-1

      CDX-2

    • Other IHC stains depending on results of above listed stains and clinical features

    • Consider gene signature profiling of biopsy specimen for tissue of origin

Where appropriate:

  • Electron microscopy

  • Cytogenetic analysis

  • Molecular profiling of biopsy specimen with next generation sequencing (NGS)

Focused Work-up

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Focused Work-up
Presentation Men Women
Head and neck or supraclavicular adenopathy

  • ENT exam

  • Testicular ultrasound

  • ENT exam

  • Mammography, ER/PR

  • Pathologic evaluation
Axillary adenopathy

  • Mammography

  • Mammography, ER/PR

  • (Consider ultrasound or MRI)
Mediastinal involvement

  • HCG/AFP

  • HCG/AFP

  • Mammography, ER/PR
Chest (effusion and/or nodules) involvement

  • Bronchoscopy

  • Mammography, ER/PR

  • CA 125
Peritoneal involvement

  • Chest/abdominal/pelvic CT

  • PSA

  • Intravaginal ultrasound

  • Mammography, ER/PR

  • CA 125
Retroperitoneal mass

  • Ultrasound

  • HCG/AFP

  • Testicular ultrasound

  • Chest/abdominal/pelvic CT

  • Mammography, ER/PR

  • CA 125
Inguinal adenopathy

  • Anoscopy/colonoscopy

  • Anoscopy/colonoscopy

  • Mammography, ER/PR

  • CA 125
Hepatic involvement

  • Colonoscopy

  • AFP

  • Colonoscopy

  • AFP

  • Mammography, ER/PR
Skeletal involvement

  • Bone scan

  • Bone scan

  • Mammography, ER/PR
Brain involvement  

  • Mammography, ER/PR
Greco FA, Hainsworth JD. In: DeVita VT Jr et al, editors. Cancer: Principles & Practice of Oncology, 10th ed. Philadelphia: Wolters Kluwer; 2015:1720–1737

Survival

All Patients With First-Line Empiric Chemotherapy

  • 1-Year survival: 35–40%

  • 2-Year survival: 15–20%

  • 3-Year survival: 10–15%

  • 5-Year survival: 10%

  • 8-Year survival: <10%

Survival varies by histology and clinical subsets

Expert Opinion

General: In the past for most patients who did not fit into ...

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