Ovarian Cancer: Classification

The following entities are distinguished according to histologic criteria:

  • Borderline and epithelial tumors (60-80% of all ovarian cancers, age-dependent: Increase with increasing age)
    • Endometrioid carcinoma
    • De-differentiated carcinoma
    • Mixed carcinoma
    • Clear cell carcinoma
    • Mucinous carcinoma
    • Squamous epithelial
    • Low-grade serous carcinoma – when low-grade serous carcinoma (LGSC) is indicated, additional subclassification should be made between carcinoma and invasive implants of a borderline serous tumor (WHO 2004)
    • Undifferentiated/unclassified carcinoma.
    • Transitional cell carcinoma
  • Germline stromal carcinomas (about 5% of all ovarian carcinomas, 2/3 are hormone active (estrogen, progesterone, testosterone and others, no age dependence)).
    • Granulosa stromal cell tumors
      • Granulosa cell tumor
        • Adult type
        • Juvenile type
      • Tumor of the thekom fibroma group
        • Thekom
        • Fibroma
        • Fibrosarcoma
    • Sertoli stromal cell tumors
      • Sertoli stromal cell tumor
      • Leydig cell tumor
      • Sertoli-Leydig cell tumor
    • Gynandroblastoma
      • Steroid cell tumor
  • Germ cell tumors (approximately 3-5% of all ovarian cancers, peak age: 18-23 years).
    • Chorionic carcinoma
    • Dysgerminoma
    • Endodermal sinus tumor (yolk sac tumor, yolk sac tumor = YST).
      • Glandular
      • Hepatoid
    • Embryonal carcinoma
    • Mixed germ cell tumors
    • Polyembryoma
    • Teratoma
      • mature
        • Fetiform (homunculus)
        • Solid
        • Cystic(dermoid cyst)
      • Immature
      • monodermal specialized
        • Carcinoid
        • Struma ovarii
  • Metastases (about 15%)
    • Endometrial carcinoma (cancer of the uterus)
    • Gastrointestinal carcinoma (cancer of the gastrointestinal tract).
    • Mammary carcinoma (breast cancer)

WHO classification (2003): staging.

TNM Criteria
T1 Tumor limited to the ovaries (ovaries)
1a
  • Tumor confined to one ovary
  • Capsule intact
  • No tumor on the surface of the ovary
1b
  • Tumor confined to both ovaries
  • Capsule intact
  • No tumor on the surface of both ovaries
1c
  • Tumor confined to one or both ovaries
  • Capsular rupture
  • Tumor on the surface of the ovaries or tumor cells in the ascites (abdominal dropsy) or peritoneal lavage fluid
T2 Tumor affects one or both ovaries and spreads to the lesser pelvis
2a Spread to and/or implants on the uterus and/or fallopian tubes
2b Spread to other tissues of the lesser pelvis
2c
  • Spreading in the small basin 2a/2b
  • Tumor cells in ascites or peritoneal lavage fluid.
T3
  • Tumor affects one or both ovaries
  • Histologically proven peritoneal metastases (daughter tumors) outside the pelvis and/or regional lymph node metastases
3a Microscopic peritoneal metastases outside the pelvis
3b
3c
Nx No statement can be made about regional lymph node metastases
N0 No metastases in the regional lymph nodes
N1 Metastases in the regional lymph nodes
M0 no distant metastases
M1 Distant metastases

It is expected that the TNM classification will be aligned with the FIGO classification in the near future. FIGO classification (2014): staging.

FIGO stage Criteria
I Tumor confined to the ovaries (ovaries)
A
  • Tumor confined to one ovary
  • Capsule intact
  • Surface free
  • Negative rinse cytology
B Tumor confined to both ovaries, otherwise as IA.
C Tumor confined to one or both ovaries
1 iatrogenic capsular rupture
2 Perioperative capsular rupture or tumor on ovarian surface
3 Malignant (malignant) cells in ascites or in flush cytology
II
  • Tumor confined to one or both ovaries
  • Cytologically or histologically proven spread in the lesser pelvis.
  • Or primary peritoneal carcinoma
A Spread to and/or implants on the uterus and/or fallopian tubes
B Spread to other pelvic tissues
III
  • Tumor confined to one or both ovaries
  • Cytologically or histologically proven spread outside the pelvis
  • And/or retroperitoneal lymph node metastases.
A Retroperitoneal lymph node metastases and/or microscopic metastases outside the pelvis
1 Retroperitoneal lymph node metastases only.
i Metastases ≤ 10 mm
ii Metastases > 10 mm
2 Microscopically detectable spread to the peritoneum (abdominal cavity) outside the lesser pelvis with or without retroperitoneal lymph node metastases
B Macroscopic spread to the peritoneum outside the lesser pelvis ≤ 2 cm with or without retroperitoneal lymph node metastases (includes spread to the liver capsule and spleen)
C Macroscopic spread to the peritoneum outside the lesser pelvis > 2 cm with or without retroperitoneal lymph node metastases (includes spread to the liver capsule and spleen)
IV Distant metastases with the exception of peritoneal metastases.
A Pleural effusion with positive cytology
B
  • Parenchymal metastases of the liver and/or spleen.
  • Metastases to organs outside the abdomen (including inguinal lymph node metastases and/or other lymph node metastases located outside the abdomen)

FIGO: International Federation of Gynecology and ObstetricsNote: Stage II C of the old FIGO classification is omitted. The following grading (assessment of the degree of differentiation of tumor tissue) is performed for ovarian cancer:

  • G1 – well-differentiated tissue
  • G2 – moderately differentiated tissue.
  • G3 – poorly differentiated tissue
  • G4 – undifferentiated tissue

TNM classification (2017) and FIGO classification.

TNM FIGO Definition
TX Primary tumor not known, no information available
T0 No evidence of tumor
T1 I Tumor confined to the ovaries (ovary) or tubes (fallopian tubes)
T1a IA Tumor confined to one ovary (capsule intact) or one tube (serosa intact), ovarian or tubal surface tumor-free, negative purge cytology
T1b IB Tumor involvement of both ovaries (capsule intact) or both tubes (serosa intact), ovarian or tubal surface tumor-free, negative purge cytology
T1c IC Tumor affecting one or both ovaries or tubes with evidence of any of the following:
T1c1 IC1 Iatrogenic capsular (serous) rupture
T1c2 IC2 Preoperative capsular (serous) rupture or tumor on ovarian or tubal surface
T1c3 IC3 Malignant cells detectable in ascites (abdominal dropsy) or on irrigation cytology
T2 II Tumor affecting one or both ovaries or tubes with cytologically or histologically proven spread to the lesser pelvis or primary peritoneal carcinoma
T2a IIA Spread and/or tumor implants to uterus (womb) and/or tubes and/or ovaries
T2b IIB Spread to other intraperitoneal structures in the area of the small pelvis

Summary of the graduation of carcinomas according to the 2014 World Health Organization (WHO) classification.

Graduation Explanation/Remark
Serious “Low-grade” (G 1) – –
“High-grade” (G3) – –
Mucinous No uniform graduation according to WHO In practice, often graduation based on endometrioid carcinomas
Seromucinous Not yet established – –
Endometrioid G1, G2, G3 – –
Clear cell Always G3 – –
Malignant Brenner tumor No graduation – –
Undifferentiated carcinomas and carcinosarcomas. No graduation, considered highly malignant – –