Ovarian Cancer
Of all the cancers arising in the body, ovarian cancer is the most common cause of peritoneal
cancer
What is Ovarian Cancer?
Ovarian Cancer is a cancer that arises from the ovaries that are part of the female reproductive system. It is the fourth most common ‘female cancer’ and the 8th most common cancer in women. Ovarian cancer originates from the surface lining (cells on the surface) of the ovaries. In rare cases, it starts from the peritoneum which is the membrane lining the contents of the abdomen and pelvis.
Recent research has shown a large proportion of these cancers arise from the fallopian tubes that transport eggs from the ovaries to the uterus. These tubes are also lined by cells that line the ovarian surface and give rise to ovarian cancer.
What is Ovarian Cancer?
Among all the cancers, ovarian cancer has the highest likelihood of spreading to the peritoneum. In many ways this cancer is similar to primary peritoneal cancers. In all other cancers (except primary peritoneal cancers), peritoneal cancer is stage IV disease, however, in ovarian cancer, peritoneal cancer spread is seen in the second and third stages (Stages II and III).
The chances of spreading to other organs like the liver, lungs and bones are lower in ovarian cancer.
The other peculiarity is that 80% of the ovarian cancers are diagnosed at a late stage- the tumor grows in the ovaries and spreads to the peritoneum without producing any signs of symptoms. It is only when the cancer has widespread and has produced swelling of the abdomen, difficulty in eating and breathing that it is diagnosed. In some women it is picked up early when scans are performed for other non-specific complaints like abdominal pain or urinary problems. The spread of cancer to the peritoneum is also very rapid in these patients and often develops only within a few months.
The Treatment
The standard treatment for ovarian cancer is a combination of surgery and chemotherapy. Surgery includes removal of the uterus and ovaries, the omentum and other regions bearing tumour. After the patient has recovered from the surgery, six doses or cycles of chemotherapy are given to the patient.
In some patients, when the disease is very extensive, chemotherapy is given first and surgery is performed after 3-4 cycles of chemotherapy. The remaining cycles of chemotherapy are given after surgery. Though the initial response to this treatment is good, in 60-70% of patients with ovarian carcinoma, usually the disease comes back in the peritoneum. To prevent this from happening or to delay recurrence, some patients with extensive disease are offered maintenance therapy for 1-2 years.
Whether chemotherapy is administered first or whether the surgery is performed first, radical surgery is essential to prolong the survival and delay recurrence. With these current treatments, less than half the patients live for five years or more as the disease comes back in the majority of the patients.
Cytoreductive Surgery V/s Debulking Surgery
Conventional surgery that is performed for ovarian cancer is referred to as ‘debulking surgery’. The uterus and ovaries are removed along with the omentum and regional nodes. Peritoneal disease is usually not addressed or only small areas of the peritoneum are removed.
In cytoreductive surgery, the entire region of the peritoneum that has tumor deposits is removed. In addition, some areas that have a higher chance of bearing microscopic disease are removed like the greater and lesser omentum. This is a more effective way to treat the disease. In addition to the disease or tumor deposits that are visible to the surgery, there is a very high chance of microscopic or invisible disease in the surrounding peritoneum that seems to be normal. In cytoreductive surgery, this peritoneum is removed which reduces the probability of the tumor coming back. It also leads to a longer survival.
HIPEC for Ovarian Cancer
HIPEC adds to the benefit of radical surgeries. It helps in treating the microscopic disease more effectively leading to reduced risk of recurrence and delays the recurrence as well. Some studies have also shown that the incidence of peritoneal recurrence is reduced with HIPEC.
The most common chemotherapy drug used for HIPEC is Cisplatin. In ovarian cancer, cisplatin resistance is a major problem leading to early recurrence and shorter survival. Heat used in HIPEC can be useful in overcoming Cisplatin resistance.
Very old and frail patients may not be able to tolerate HIPEC. Similarly those who have kidney dysfunction, uncontrolled diabetes or other major health issues are not subjected to HIPEC to avoid severe complications.
Currently, HIPEC is recommended to only select a group of patients with ovarian cancer. It is only performed for patients with ovarian cancer undergoing surgery after a few cycles of chemotherapy. In this scenario, performing HIPEC in addition to cytoreductive surgery increases the lifespan by one year or more.