Cervical cancer begins in the cells of the cervix, the lower part of the uterus that connects to the vagina. The spread of cancer cells from a primary tumor to other parts of the body is known as metastasis. Understanding how this cancer progresses from its site of origin provides clarity about the disease. Recognizing the common pathways and destinations of spread is important for understanding progression.
Understanding the Pathways of Spread
Cervical cancer can spread from the cervix through three main biological mechanisms, moving from local tissue to distant organs. The most common initial method is direct invasion, where the cancer simply grows outward into the adjacent tissues and structures. This local extension affects the organs immediately surrounding the cervix.
A second, highly frequent pathway is lymphatic spread, which involves cancer cells entering the lymphatic system. Once inside these vessels, cancer cells can travel to nearby lymph nodes, where they can multiply and potentially move further.
The third method of spread is hematogenous dissemination, which occurs when cancer cells enter the bloodstream. The circulatory system provides a direct route for cells to travel to organs far from the pelvis. This route is associated with more advanced disease or aggressive types of cervical cancer.
Regional Spread: Pelvic Structures and Lymph Nodes
The initial spread of cervical cancer focuses on structures immediately surrounding the cervix and the regional lymph node chains. Cancer cells frequently spread by direct extension laterally into the parametrium, the tissue surrounding the uterus. They can also spread distally to involve the upper and lower portions of the vagina.
Anteriorly, large tumors can extend to the bladder, while posterior spread can involve the uterosacral ligaments and the rectum. Involvement of these adjacent organs is often classified as locally advanced disease. Simultaneously, the cancer primarily travels through the lymphatic channels to the pelvic lymph nodes, which is a defining step in disease progression.
The initial groups of lymph nodes involved are the obturator, internal iliac, and external iliac nodes, all located within the pelvis. From these nodes, the cancer may progress in an orderly fashion up the common iliac chain. This progression can lead to the involvement of the para-aortic nodes located near the aorta in the abdominal cavity, which is considered a more advanced regional spread.
Distant Spread: Common Sites of Metastasis
Distant spread, or metastasis to sites outside the pelvis, occurs when cancer cells utilize the bloodstream to travel to remote organs. The lungs are the most common site for cervical cancer to metastasize distantly, with some studies finding this in nearly 38% of single-site metastatic cases. Cancer cells often form nodules or masses in the lung tissue.
The skeletal system is the next most frequent distant target, particularly the bones of the spine and hips. This bone involvement is usually due to hematogenous spread and can result in the destruction of bone tissue. The liver is the third most common site for distant metastasis, where the cancer can affect liver function.
Less commonly, the cancer can spread to other areas, including distant soft tissues or the brain. Metastasis to these distant sites is categorized as the most advanced stage of the disease. The specific location of distant spread is a significant factor in determining the overall plan for managing the cancer.
Recognizing Signs of Advanced Spread
When cervical cancer has spread beyond the local region, symptoms often arise that are specific to the organ or structure that is newly involved. If the cancer has spread to the bones, a persistent ache or pain is a common sign, sometimes severe enough to wake a person at night. This skeletal involvement can also lead to weakened bones that are more susceptible to breaking.
Spread to the lungs may cause a cough that does not go away, breathlessness, or, in some instances, a build-up of fluid around the lungs. When the liver is affected, symptoms can include discomfort on the right side of the abdomen, loss of appetite, or jaundice, which is a yellowing of the skin and eyes.
Swelling in the legs, known as lymphedema, can occur if cancer cells obstruct the flow of fluid through the pelvic lymph nodes. If the cancer has grown into the bladder or rectum, a person may experience painful or difficult urination, or pain and bleeding from the rectum. These specific signs indicate that the cancer has progressed and requires prompt medical attention.