Cervical cancer originates in the cervix, the lower, narrow part of the uterus connecting to the vagina. Like other malignant tumors, this cancer can spread from its primary site to other areas of the body, a process known as metastasis. Understanding the pathways and common destinations of this spread is crucial because the extent of the disease directly influences treatment planning and overall prognosis.
Local and Regional Spread
The initial spread of cervical cancer typically involves direct growth into nearby pelvic structures through local extension. Cancer cells move outward from the cervix to invade surrounding tissues, such as the upper two-thirds of the vagina and the parametria (fibrous tissues next to the uterus). This localized growth can eventually involve other physically close organs, including the lining of the bladder or the rectum.
A second common route of expansion is through the lymphatic system, where cancer cells travel to regional lymph nodes. The first nodes encountered are the pelvic nodes, including the obturator, internal iliac, and external iliac groups. Involvement of these nodes classifies the disease as regionally advanced.
Distant Metastasis Sites
When cervical cancer spreads beyond the pelvic region, it is typically carried through the bloodstream (hematogenous dissemination) and classified as distant metastasis.
The most frequent site for this distant spread is the lungs. Metastases here can lead to symptoms such as chronic cough or shortness of breath.
The liver is the second most common location for distant spread. Liver metastases can impair the organ’s ability to filter blood and produce essential proteins.
Bone metastasis is the third primary distant site, often affecting the spine and the bones of the pelvis. These cancerous lesions are frequently lytic, causing bone destruction that can lead to pain or an increased risk of fractures.
Other organs, such as the brain and distant lymph nodes, are less frequent sites of metastasis but can be involved in advanced stages.
Staging the Spread
The International Federation of Gynecology and Obstetrics (FIGO) staging system is the standardized method used to classify the extent of cervical cancer spread. This system is divided into four main stages, with higher numbers indicating more extensive disease. Stage I cancers are strictly confined to the cervix itself.
Progression to Stage II signifies that the cancer has grown outside of the cervix and uterus but has not yet reached the pelvic wall or the lower third of the vagina.
Stage III is designated when the tumor has extended to the pelvic wall, the lower third of the vagina, or has caused kidney obstruction due to ureter involvement. The presence of cancer in pelvic or para-aortic lymph nodes is also classified as Stage III.
The most advanced classification is Stage IV, divided into two subcategories. Stage IVA indicates spread to adjacent organs within the pelvis, specifically the lining of the bladder or rectum. Stage IVB is reserved for cases where the cancer has metastasized to distant organs outside of the pelvis, such as the lungs, liver, or bones.
Detecting Metastasis
Diagnosing the extent of cervical cancer spread relies heavily on advanced medical imaging to determine tumor size and locate metastatic deposits. Computed Tomography (CT) scans visualize the abdomen and pelvis, primarily to identify enlarged lymph nodes or masses in distant organs like the liver.
Magnetic Resonance Imaging (MRI) provides detailed images of soft tissues, making it effective for assessing the size of the primary tumor and whether it has invaded the surrounding pelvic structures.
Positron Emission Tomography (PET) scans, often combined with CT (PET/CT), are valuable for detecting metastatic sites throughout the entire body. PET/CT uses a radioactive glucose tracer that accumulates in highly metabolic cancer cells, offering high sensitivity for identifying lymph node involvement and distant metastases.
While imaging suggests the presence of cancer spread, a biopsy remains the definitive method. This procedure involves removing a small piece of suspicious tissue for microscopic examination to confirm malignant cells.