Known by the shorter and much easier to remember acronym HIPEC, Hyperthermic Intraperitoneal Chemotherapy actually constitutes one half of a two-part surgery in which it is combined with cytoreductive surgery. This treatment is used for patients who have an advanced tumour which is isolated in the peritoneal or the belly region.
Initially, when there is a disease spreading in the peritoneum, doctors used to opt for conventional treatment procedures such as a cytoreductive surgery and then give chemotherapy through an IV line. But, doctors know that if chemotherapy is given through the vein, it will reach the blood and the organs, but will not reach the peritoneal cavity in sufficient concentration. This is because, the depth and penetration of this chemo to kill the cancer cells Is only 5 mm. In order to overcome that, some form of chemotherapy is given into the tummy or the peritoneum, which is called intraperitoneal chemotherapy. It was found that if the chemo was given at normal body temperature of about 37°C, the efficacy wasn’t very high.
Various research studies found that if chemotherapy was combined with high temperature in the range of 41-42°C, which is called Hyperthermia, the efficacy of the chemo doubled or even tripled, and the depth of penetration also increased manifold. As a result, Hyperthermic Intraperitoneal Chemotherapy (HIPEC) is more effective in killing the cancer cells which are spread in the tummy region. This technique needs a specialized, dedicated team, HIPEC machine and trained doctors and is done immediately after the cytoreductive surgery.
How does HIPEC work?
It is a known phenomenon that if the chemotherapy bakes the cancer cells which have spread into small nodules in the tummy, then it is penetrating up to 1 cm, and not just 5 mm. So the cancer cells are on sustained burying of a thin layer of chemo fluid and are killed. In the case of hyperthermia, where the body temperature of the chemo fluid is increased to 41-42°C , it kills the DNA, RNA and lysosomes and destroys the cancer cells. Once they are destroyed, the chemo can penetrate deep inside and kill the remaining cancer cells. So, along with the macroscopic or the visible cancer cells, microscopic ones not visible to the doctor’s eye are also taken care of by Hyperthermic Intraperitoneal Chemotherapy (HIPEC) technique.
Techniques of HIPEC delivery
HIPEC consists of three components:
It has a narrow therapeutic temperature range of 41 – 43° C. If the temperature is less than 41°C, it is not beneficial, while excess of 43°C results in complications.
The circulating speed of the fluid that circulates in the tummy with chemo should be at least 1 litre/minute.
The pressure should be around 14-15 Pa.
To ensure such precise parameters, conventional heart-lung or other machines are of no use. A dedicated HIPEC machine is essential which can measure and maintain the flow rate, the temperature in all the quadrants of the tummy and the volume. The procedure lasts for 90 minutes.
What are the drug regimens in use for HIPEC?
There is a selection criteria for the drugs needed for intraperitoneal chemo:
Heat Sustainability: It should not be destroyed by high temperatures.
It should be capable of reaching maintaining high levels of concentration in the tummy or the peritoneal cavity.
It is specific to the type of cancer. For example, in cases of carcinoma ovary, usually a drug called cisplatin is prescribed, while for colon or rectal cancers oxaliplatin is used. While these are the most common drugs used in HIPEC, there are many other drugs which are used in extraordinary circumstances.
Role of HIPEC in Advanced Ovarian and Colorectal Cancer
In India, most of the ovarian cancer patients visit a doctor when they are in Stage 3C, and colorectal cancer patients too usually seek medical opinion when it is quite late and the disease is in its advanced stage. If a person has Stage 4 colorectal cancer with peritoneal spread, conventional treatments will not be able to cure him/her. In addition to systemic chemo, if cytoreductive surgery along with HIPEC is done on a patient who has responded well to chemo and where the cancer has not spread outside the tummy, the chances of curing him/her is more than 60-75% with a five to ten year life span which is a tremendous improvement in colorectal cancer. HIPEC and cytoreductive surgery is the only ray of hope for those affected with advanced stage 4 ovarian cancer or recurrent cancer.
What are the complications after HIPEC?
It is important to note that HIPEC is tough on the body. It is experiencing the compounding effects of a major surgery, addition of chemo and an increase in temperature. The effects of fever, i.e., increase in metabolic rate, sweating, weakness, high heart rate and low urine output are experienced on a magnified scale. For the first one or two weeks after the HIPEC procedure, the patients are prone to bacterial, fungal and/or viral infections due to decreased immunity and need constant monitoring. The intestine takes some days to recover, so adequate nutrition including protein and albumin through the parenteral route. The doctors must perform hourly mobilizations so the patients don’t develop venous thrombosis or lung infection. In general, the complication rate is about two fold more than normal surgery, but highly manageable.
Notwithstanding the possible complications of HIPEC, it still has several distinct advantages. It is found that in peritoneal surface cancers like those affecting the stomach, ovaries, colon etc., if only surgery is done, the time taken for curing ranges from 24-36 months for a patient. If cytoreductive surgery is carried out and intravenous chemo is given, the cure rate drops to about 32 months. Now, if along with this surgery, HIPEC procedure is carried out with the help of a dedicated machine, the patients can be cured within a couple of months. They have more than 50-60% chance of living beyond five to ten years with an excellent quality of life. Therefore, incorporating the HIPEC technique gives a fresh lease of hope to tackle this malignant disease for which there would otherwise be no cure is available. Hyperthermic Intraperitoneal Chemotherapy(HIPEC) is the only option for peritoneal surface malignancies.
It reduces the side effects of chemotherapy.
It improves the efficacy of chemotherapy absorption and increases the susceptibility of cancer cells.
It helps in concentrating the chemotherapy within the tummy.