Ovarian cancer (OCa) accounts for 2.1% of all cancer-related deaths. Only ~19% of OCa cases are diagnosed in the early stages. Early stage disease is associated with a five-year SR of ~93%.¹ Endometrial cancer (ECa) is the sixth most common cancer in women.⁵ The five-year SR of ECa in the early stages is ~96% and ~20% if it has spread.⁶

Primary vaginal cancer (VCa) vaginal cancer is rare (~1%–2% of all gynaecological cancers). Primary VCa excludes any involvement of the cervix and/or vulva as well as any malignant lesion arising in the vagina within five years after the treatment of CCa.⁷ The five-year SR of VCa is ~96% in the early stages and between 18%-36% if it has spread.⁶

Vulvar cancer (VuCa) is also rare (incidence rate of 1.5–2.4 per 100 000 women per year). The five-year SR for early stage disease is ~87% and ~22% if it has spread.⁸

Recommendations for the use of PET-CT

The International Atomic Energy Agency (IAEA) recently published a report on the PET–CT for the Management of Cancer Patients: A review of the Existing Evidence.³

According to the IAEA, PET is now the standard of care for most tumour types. Recommendations for CCa, OCa, ECa and VuCA are included in the review. This is what they recommend:³

PET/CT in cervical cancer

In stage 1, PET is a valuable adjunct to conventional imaging methods, namely CT and magnetic resonance imaging (MRI). Although MRI is the preferred method for the evaluation of local extension, PET is superior for the evaluation of lymph node involvement and sensitive for the detection of distant metastases.³

In high-risk cases, PET should be performed three- to six months after the completion of chemoradiation. In recurrence, PET is recommended for patients where metastasis is suspected. For locally advanced tumours, the detection of metastasis in para-aortic lymph nodes by PET may lead to modification of the treatment fields. This is particularly important in CCa.³

According to the European Society for Medical Oncology CCa (ESMO) guideline, CT can detect pathological lymph nodes, while MRI can determine tumour size, degree of stromal penetrations, parametrial involvement, vaginal extension and corpus extension with high accuracy.⁹

PET has been shown to accurately delineate the extent of disease, particularly in lymph nodes that are not macroscopically enlarged and in distant sites, with high sensitivity and specificity. In early-stage disease, PET-CT has a sensitivity of 53%–73% and specificity of 90%–97% for the detection of lymph node involvement.⁹

PET/CT in ovarian cancer

According to the IAEA, PET may be used for assessing response in patients with known metastatic disease after multimodality therapy. Furthermore, studies have shown that PET is superior to CT and complementary to MRI in patients with suspected recurrence.³

In advanced disease, PET may be recommended to exclude distant metastasis and may be used in the workup for patients considered for surgery and/or locoregional therapy.³

The ESMO OCa guideline recommends PET-CT, or diffusion-weighted whole-body MRI as part of the pre-operative diagnostic workup to assess the extent of disease.¹⁰

PET/CT in endometrial cancer

The IAEA recommends PET in advanced disease to exclude distant metastasis. Furthermore, PET may be used in the workup for patients considered for surgery and/or locoregional therapy.³

The ESMO ECa guideline recommends clinical and gynaecological examination, transvaginal ultrasound, and pelvic MRI as part of the pre-operative work-up. Additional imaging tests (eg thoracic and abdominal CT scan and/or PET-CT) may be considered in those patients at high-risk of extra pelvic disease.¹¹

PET/CT in vaginal and vulvar cancers

The IAEA recommends PET in advanced VuCa to exclude distant metastasis and in the workup for patients considered for salvage surgery and/or locoregional therapy.³

Several studies have suggested that PET-CT is useful for detecting nodal and distant metastases in VCa and VuCa. Few studies have reported on the use of PET-CT in VCa.¹³

One study conducted in 2005 demonstrated that PET can detect primary tumours in VCa, and abnormal lymph nodes, more often than conventional CT. A more recent study showed that PET-CT can accurately identify nodal involvement.¹³

An early study found that PET-CT had a sensitivity of 80%, specificity of 90%, and a positive predictive value (PVV) of 80% in identifying VuCa lymph node metastases, while a later study reported a sensitivity of 50%, a specificity of 100%, a PPV of 100%, and a negative predictive value of 57.1%. The high PPV supports the notion that PET could be used prior to surgical staging in patients with stage 3 disease.¹³

In summary, PET-CT is an invaluable advanced diagnostic imaging modality in oncology with a variety of applications, including initial staging of cancer, assessment of response to therapy, restaging, and longitudinal surveillance for recurrence. 

References

1. Virarkar M, Vulasala SS, Calimano-Ramirez L, et al. Current Update on PET/MRI in Gynecological Malignancies—A Review of the Literature. Curr Oncol, 2023.
2. Centres for Disease Control and Prevention [Internet]. Basic Information About Gynecologic Cancers. Accessed 5 April 2023. Available at: https://www.cdc.gov/cancer/gynecologic/basic_info/index.htm
3. International Atomic Energy Agency (IAEI) [Internet]. PET–CT for the Management of Cancer Patients: a Review of the Existing Evidence. Available at: https://www-pub.iaea.org/MTCD/Publications/PDF/PUB1993_web.pdf.
4. National Cancer Institute [Internet]. Cervical Cancer Prognosis and Survival Rates. Available at: https://www.cancer.gov/types/cervical/survival#:~:text=When%20cervical%20cancer%20is%20diagnosed,relative%20survival%20rate%20is%2059%25. Accessed: 5 April 2023.
5. CancerNet [Internet]. Uterine cancer. Available at: https://www.cancer.net/cancer-types/uterine-cancer/statistics. Accessed 5 April 2023.
6. World Cancer Research Fund [Internet]. Endometrial cancer statistics. Available at:
7. https://www.wcrf.org/cancer-trends/endometrial-cancer-statistics/. Accessed 5 April 2023.
8. American Cancer Society [Internet]. Endometrial cancer survival rates. Available at: https://www.cancer.org/cancer/endometrial-cancer/detection-diagnosis-staging/survival-rates.html. Accessed 5 April 2023.
9. Marth C, Landoni F, Mahner S, et al, on behalf of the ESMO Guidelines Committee. Cervical cancer: ESMO Clinical Practice Guidelines. Ann of Oncology, 2017.
10. Colombo N, Sessa C, du Bois A, et al. ESMO–ESGO consensus conference recommendations on ovarian cancer: pathology and molecular biology, early and advanced stages, borderline tumours and recurrent disease. Ann Oncol, 2019.
11. Oskin A, Bosse TJ, Creutzberg, et al, on behalf of the ESMO Guidelines Committee Endometrial cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Ann Oncol, 2022.
12. Jhingran A. Updates in the treatment of vaginal cancer. International Journal of Gynecologic Cancer, 
13. Robertson NL, Hricak H, Sonoda Y, et al. The impact of FDG-PET/CT in the management of patients with vulvar and vaginal cancer. Gynecol Oncol, 2016.