One of the most important questions in oncology today is why does cancer recur? Despite extensive treatments like chemotherapy, surgery and radiation therapy, there are chances of cancer coming back. Most of the cancers recur in the first 5 years, while many people have stayed cancer-free for years and even decades before their cancer returns.

Cancer specialist doctors in Delhi are dealing with thousands of patients every year. According to recent research, Delhi has recorded the highest number of cancer incidences in the country. Not only that, being the national capital and a metropolitan city, there a huge influx of people from the neighboring villages coming for oncology treatment in Delhi. even though it is not the most economically friendly treatment, is provided by cancer specialist doctors in Delhi, who have gone though rigours medical training for years, supported by a highly qualified nurse workforce.

One will find among the best oncology hospitals in Delhi according to their needs and the type of treatment they are looking for, in their state of the art infrastructure. India has several well-experienced doctors who provide radiation oncology in Delhi.

Radiation oncology in Delhi is equipped suitably for patients looking to get a world class treatment. The treatments require the patients to be under specialized care and medication. These treatments can be very expensive especially if you are going to the best oncology hospitals in Delhi. It is always better to get health insurance.

Usually, the treatments that are used for cancer, is used to prevent the cancer cells from spreading or persisting and also from finding a chance to hide. But in many cases, in spite of the treatments, some cells are left behind. Recurrence of cancer is a major cause of illness and death among patients, so understanding why the cancer returns is very crucial in increasing the survival rates for the patients. This is done in hopes that the knowledge in this area will increase the survival rates as the patients will be well aware of the red flags if any. It’s important to keep in mind that it does not take a lot of leftover cells after the treatment for cancer to return.

Sometimes, even if no cancerous cells are seen at the edges of tumors, some cells may have already spread via the lymphatic system to the nearby tissues. It can also spread through the bloodstream to other regions of the body. They often go undetected. Both radiation therapy and surgery are considered as local treatments because they do not treat cancer cells that have gone beyond the treatment region. Also, radiation therapy may not kill all the cancerous cells. How radiation works is it damages the DNA both in the normal cells and the cancer cells. Normally, the cells recover after the radiation and in this case the cancer cells may also recover.

So why won’t chemotherapy kill the cancer cells?Unlike the radiation therapy and surgery, chemotherapy is considered to be a systemic therapy which is designed to treat not only the cancerous cells, but also to get rid of the cells that have spread beyond the treatment regions. Most of the chemotherapy drugs, at some point, work towards the process of cell division. Not every cancer cell is dividing at all times, so the cancer cells which are not dividing or the cells which may be at a different stage of cell division may survive the chemotherapy. This is the reason why some people may get more than one session of chemotherapy and get treated with more than one drug.

There are few theories and researches to answer how cancer cells can hide for years or even decades. There seems to be an ability of the cancer cells to hide for an extended amount of time. To illustrate an example, around 20 to 40 percent of estrogen receptor-positive breast cancer which recurs, occur after years or decades after cancer has been treated successfully. One of these researches is also of cancer stem cells. Normally, one may think of cancer cells as having some hierarchy but in this case, the cancer stem cells would be stronger than the other cancer cells, which mean that they are more resistant to treatments probably because they divide at a much slower rate). So while many treatments will kill the cancer cells, these cells may remain alive, ready to grow again in some time.