Ovarian Carcinoma



Ovarian Carcinoma


Todd M. Blodgett, MD

Alex Ryan, MD

Hesham Amr, MD









Axial graphic shows a heterogeneous pelvic mass with areas of central necrosis and peripheral areas of nodularity image, compatible with ovarian carcinoma.






Axial fused PET/CT shows the areas of peripheral nodularity image with intense activity.


TERMINOLOGY


Abbreviations and Synonyms



  • Ovarian carcinoma, carcinoma of the ovary, ovarian cancer


Definitions



  • Primary malignancy of ovary



    • Epithelial (90%)



      • Arises from germinal epithelium on outside of ovary


    • Stromal (6%)



      • Arises from connective tissue


      • Low rate of metastasis


    • Germ cell (3%)



      • Teens/young women


      • Highly curable


  • Staging of ovarian cancer



    • Stage I: Confined to one or both ovaries


    • Stage II: Spread to uterus/fallopian tube, within pelvis


    • Stage III: Lymph nodes, abdominal cavity


    • Stage IV: Outside abdomen, intrahepatic metastases


IMAGING FINDINGS


General Features



  • Best diagnostic clue: Solid or complex cystic mass arising from ovary ± ascites


  • Location



    • Primary generally found in ovary


    • Metastases most common to peritoneum, omentum


    • Rare intrahepatic metastases


    • Three main routes of lymphatic spread



      • Accompanying ovarian blood vessels cranially to para-aortic and paracaval nodes


      • Following subovarian plexus in broad ligament to obturator and pelvic nodes


      • Following round ligament to external iliac and inguinal nodes


  • Size



    • Variable



      • However, most ovarian carcinoma detected late, so tumors tend to be large


Imaging Recommendations



  • Best imaging tool




    • Most common: Transvaginal ultrasound followed by MR &/or CT for evaluation of metastasis



      • Risk of malignancy index (RMI) calculated using transvaginal ultrasound results, CA-125 blood level, menopausal status


    • Consider PET/CT for most complete staging



      • Especially use PET/CT for suspected recurrence, particularly with mild rise in CA-125


  • Protocol advice: Consider using contrast-enhanced CT as part of the PET/CT scan


CT Findings



  • Primary lesion usually complex cystic mass with mural nodularity


  • In general, malignancy suggested by thickness and irregularity of cavity walls, septae, enhancing nodules


  • Sensitivity 92% for peritoneal metastases


  • GI contrast especially helpful for distinguishing pelvic viscera from intestinal tract


  • Primary use of CT scanning is to evaluate metastatic disease, not ovarian mass



    • For evaluation of the ovarian mass, ultrasonography and MR are more valuable


  • CT scanning is helpful in diagnosing cystic teratomas, 93% of which contain fat and 56% of which are calcified



    • If a large (> 10 cm) soft tissue mass is present, malignant transformation should be suspected


  • Serous cystadenoma has an attenuation similar to that of water



    • But mucinous cystadenoma has an attenuation closer to that of soft tissue


  • CT imaging has much greater sensitivity than techniques used previously



    • Detects 2-3 mm lesions in the lungs and solid viscera


  • Scans with contrast yield high-quality information about retroperitoneal lymph nodes and ureters


  • Low contrast between peritoneal tumors and adjacent soft tissues limits overall sensitivity



    • MR sensitivity in this case 91%



      • But limited in depiction of small calcified peritoneal implants, which are common in patients with serous carcinoma


  • NECT



    • Cystic adnexal mass with septations and soft tissue density papillary projections


  • CECT



    • Solid mural nodules demonstrate enhancement


    • May facilitate detection of peritoneal implants and distant metastases


  • CT angiogram: Can be used to assess vascular invasion


Nuclear Medicine Findings



  • Initial diagnosis



    • FDG PET almost never used to evaluate an adnexal mass or to evaluate for primary ovarian carcinoma


    • Pure mucinous adenocarcinoma more likely to be falsely negative by standard SUV criteria, due to low cellularity and better differentiation properties


  • Staging



    • Not currently covered by Medicare


    • Three lymph node stations with high rate of false positives: Axillary, inguinal, hilar


    • PET limited in detecting lymph node micrometastases



      • In one study, PET/CT failed to identify microscopic disease in 59% of pathologically positive lymph nodes


    • Also limited for differentiating peritoneal tumors from adjacent soft tissue or bowel activity


  • Restaging



    • PET/CT: Sensitivity > 95%, specificity 80-93%, and positive predictive value of 83-94% for detection of recurrence


    • PET has 6-8 mm limit of resolution



      • Limited in detection of small disseminated lesions (e.g., peritoneal carcinosis and mesenteric or omental recurrences)


    • Degenerative change in pelvis, such as sacroiliac arthritis, has been mistaken for recurrence



      • Active degenerative change in bone can have ↑ FDG activity



    • For detection of ovarian cancer recurrence mean sensitivity, specificity, and accuracy each 83%


    • In one study of patients with primarily subcentimeter lesions, sensitivity of FDG PET for recurrence was only 10%



      • With mean lesion size of 1.1 cm, patient-based sensitivity 81%


  • Response to therapy



    • Paucity of studies in the literature; not currently covered or recommended for evaluating response to therapy


DIFFERENTIAL DIAGNOSIS


Pelvic Inflammatory Disease



  • CT findings nonspecific


  • Disrupted fat planes


  • Thickened fascial planes


Tubo-Ovarian Abscess



  • Commonly depicted as regular mass with debris similar to that seen with endometrioma or hemorrhagic cyst


Complex Functional Cysts



  • May have intense FDG activity


Benign Ovarian Tumors



  • Includes cystadenoma, dermoid tumors


Borderline Ovarian Tumors



  • Pathologically difficult to differentiate between benign and malignant


  • Low malignant potential


Normal Physiologic FDG Activity



  • Mostly in younger premenopausal women


  • Helpful if bilateral physiologic activity present


  • Look for CT findings of corpus luteal cyst: Rind of enhancement in an otherwise normal-appearing ovary


PATHOLOGY


General Features



  • General path comments



    • Ovarian cancer spreads primarily intraperitoneally as well as to lymph nodes



      • Peritoneal fluid flows upward from pelvis to paracolic gutters and subphrenic regions, carrying tumor cells that implant on abdominal viscera


    • Common sites of metastatic implantation



      • Pelvis


      • Right hemidiaphragm


      • Perihepatic


      • Right paracolic gutter


      • Bowel


      • Omentum


    • Distant lymph nodes are involved in approximately 7% of cases of serous ovarian adenocarcinoma


  • Genetics



    • 10% of patients with ovarian cancer appear to have genetic predisposition


    • These patients may develop cancer early, between ages 30 and 50


    • One study suggested patients with BRCA gene have 60% risk of developing ovarian cancer


  • Etiology



    • Unknown


    • Number of reproductive cycles appears to be related to risk


    • Ovulation suppression may decrease cancer incidence


  • Epidemiology



    • Leading cause of death among women with gynecological malignancies


    • Third most common cancer of female reproductive organs


Microscopic Features



  • Most common histologies are papillary serous adenocarcinoma and endometrioid type


  • Serous adenocarcinoma comprises 40% of epithelial ovarian cancers


  • Psammoma bodies may be present



    • Ovarian cancer with multiple psammoma bodies may have better prognosis


CLINICAL ISSUES


Presentation



  • Most common signs/symptoms



    • Early stage: Nonspecific, pelvic pain



      • Often attributed to other causes (e.g., menstruation, irritable bowel syndrome)


    • With metastases: Abdominal/pelvic bloating, pain, pressure, early satiety, nausea/vomiting, frequent urination, feeling similar to pregnancy


  • Other signs/symptoms



    • CA-125 has accuracy of 79-95% for recurrence; increase precedes apparent recurrence by 3-6 months


    • Doubling of CA-125 above normal limit has been shown to have sensitivity of 85.9% and specificity of 91.3% for detection of recurrence


Demographics



  • Age: Average age at diagnosis 57 years


  • Ethnicity: More common among Caucasians than African-Americans


Natural History & Prognosis



  • Most patients asymptomatic until disease is in advanced stage


  • In 75-80% of patients, cancer has spread beyond ovary at diagnosis


  • Overall survival approximately 35%


  • Despite clinical advances and improved surgery, overall survival has not changed because the disease presents at advanced stage



    • 75% of patients are diagnosed in stage III/IV, and in this group the 5 year survival rate is 17%


  • Up to 85% of women ultimately relapse


  • Well-known that patients with advanced ovarian cancer have better outcome when neoadjuvant chemotherapy is performed before surgery




  • Up to 24% of ovarian tumors in premenopausal women are malignant and up to 60% in postmenopausal women


Treatment



  • Surgery, chemotherapy, radiation therapy; depends on stage of disease, institution where treated



    • Surgery for earlier stages: Total abdominal hysterectomy, bilateral oophorectomy, omentectomy, biopsy of lymph nodes/tissues


    • Surgery for later stages: Early stage surgery plus tumor debulking


    • Chemotherapy: Paclitaxel &/or platinum-based drugs


    • Radiation therapy: Stage II


  • Exploratory laparotomy done for high suspicion of malignancy



    • Only 1 ovarian cancer detected for every 8-9 benign cyst operations


  • Benefit of optimal primary cytoreductive debulking surgery is well established


  • Following debulking surgery, stage IV patients have same median survival as stage III patients


  • 75% of women have complete clinical response, but the majority of these will experience recurrence


DIAGNOSTIC CHECKLIST


Consider



  • Benign increased FDG uptake in ovaries can mimic ovarian primary malignancy



    • Look for other signs of ovarian malignancy (ascites, peritoneal implants, lymphadenopathy)


  • PET/CT valuable in patient with rising CA-125, negative anatomic imaging



    • Some claim PET is as valuable for detection of recurrence as second-look surgery and may be substituted as noninvasive option


  • PET/CT valuable to distinguish post-surgical change from recurrence


Image Interpretation Pearls



  • Serous adenocarcinoma may contain microcalcifications that can be confused with old granulomatous disease


  • Incidence of groin metastases less than 3%; isolated inguinal nodal metastasis without other nodal involvement very rare



SELECTED REFERENCES

1. Hillner BE et al: Impact of positron emission tomography/computed tomography and positron emission tomography (PET) alone on expected management of patients with cancer: initial results from the National Oncologic PET Registry. J Clin Oncol. 26(13):2155-61, 2008

2. Reinhardt MJ: Gynecologic tumors. Recent Results Cancer Res. 170:141-50, 2008

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Sep 22, 2016 | Posted by in MAGNETIC RESONANCE IMAGING | Comments Off on Ovarian Carcinoma
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