Why cancer can return after chemo

The findings indicate that participants assigned more importance to staff attitudes than to the physical environment.

By JUDY SIEGEL-ITZKOVICH
Cancer patient receiving chemotherapy 390 (photo credit: Thinkstock/Imagebank)
Cancer patient receiving chemotherapy 390
(photo credit: Thinkstock/Imagebank)
The fight against cancer is not won in a single battle. Long after a cancer has been beaten into remission, it can return. But oncologists are not sure exactly why this happens, and the debate continues. New research led by Weizmann Institute scientists in Rehovot shows that, at least for one type of blood cancer, the source of cancer recurrence is a set of cells that do not proliferate as quickly as regular cancer cells and thus are able to survive chemotherapy. The findings, which appeared recently in the journal Blood, have some important implications for the future of the war on cancer.
Cancer involves a breakdown in the mechanism that regulates the pace of cell division. When this happens, cells divide rapidly, leading to unchecked growth that overruns the body. The most common chemotherapy drugs are those that specifically attack cells undergoing rapid division, and these, indeed, often destroy all the cancer and cure the patient.
But there are also quite a few patients with this type of blood cancer who go through chemotherapy only to have the cancer return. Several explanations have been proposed for why this happens. One is that the chemotherapy does not kill every last cancer cell, leaving a few to continue dividing out of control until the disease returns in full force.
According to another explanation, chemotherapy does get all the regular cancer cells, but there is another type of cancer cell that hides in the body. As opposed to the rapidly dividing majority of cancer cells, these undergo slow division, enabling them to evade the chemotherapy drugs. These insidious cells can give rise to new rapidly-dividing cancer cells, which is why they are known as “cancer stem cells.”
Which explanation is correct? The debate is an important one because, if the first explanation holds true, improving upon the existing treatments might help, while the second implies that a completely different approach to treatment will be needed to root out the slowly-dividing cancer stem cells.
To try to resolve the debate, the team of Prof. Ehud Shapiro of the institute’s biological chemistry and applied mathematics and computer sciences departments worked with scientists and physicians from Rambam Medical Center and the Technion-Haifa Institute of Technology in Haifa. They used a method of reconstructing cell lineage trees that has been developed over the past few years in Shapiro’s lab. This method is based on the fact that the genetic material in different body cells accumulates unique mutations during cell division, and these mutations are passed on to daughter cells.
By comparing mutations, they could map out cells’ detailed “family trees” and thus determine how far back they share a common ancestor. The end product of this analysis is a tree that reconstructs the genealogy of the cells from their earliest forebears at the base of the tree to the youngest cells at the tips of the branches.
To reconstruct the cancer cell lineage tree, the team used two sets of blood samples – the first taken from leukemia patients right after the disease was diagnosed, and the second from those patients who had undergone chemotherapy and in whom the cancer had returned. The researchers could then trace the relationships of the recurring cancer cells back to see if they descended from the original cancer cells.
The lineage tree showed that, at least in some of the patients, the source of the renewed cancer was not in the rapidly proliferating cancer cells, but rather in cells that were close to the root of the tree. These cells had only divided a few times.
In other words, the cancer arose from cells that divide very slowly, making them resistant to the attacks of chemotherapy drugs.
Shapiro explained: “We know that in many cases, chemotherapy alone is not able to cure leukemia. Our results suggest that to completely eliminate it, we must look for a treatment that will not only eliminate the rapidly dividing cells, but also target the cancer stem cells that are resistant to conventional treatment.”
The Knesset Finance Committee has committed itself to the financing of a national program for reducing the number of suicides, which began this year as a pilot project. This was announced by committee chairman MK Moshe Gafni (United Torah Judaism) in a special session on suicide prevention.
The discussion was initiated by MK Avraham Michaeli of Shas who has in the past promoted several initiatives against suicide in Israel. Michaeli said the pilot project has been very successful in Ramle, Rehovot and Kafr Kana and was to wind down by the end of December because it lacked NIS 600,000.
The pilot managed to very significantly reduce the number of suicides in the three locations. There wasn’t a single case of suicide in Kafr Kana since the project began, he said. Six government ministries are partners in the project, which should be expanded and not halted, said the MK.
The project, which screens people for suicidal tendencies and treats them before it is too late, is led by the Health Ministry. Now, a budgetary problem has arisen, and its continued existence is threatened by the lack of NIS 8 million. The six ministries – which besides Health are Education, Welfare and Social Services, Industry, Trade and Employment, Absorption and Pensioners – have not committed themselves to finance a continuation, Michaeli said.
The project was described in the session by Health Ministry associate directorgeneral Dr. Boaz Lev, who said that staffers were specially trained to identify potential suicides and treat them. Multidisciplinary teams of family physicians, social workers, psychologists, mental health teams, teachers and school counsellors are integrated into the project.
Gafni demanded that the Finance Ministry’s budgets division allocate money to implement the program and asked the six ministries involved to apply for allocations.
If they are turned down, he said, they should update the Finance Committee, which would make sure during discussions of the 2013 budget that money be transferred from other uses.
Going to a hotel is fun, but it isn’t always easy for the disabled to enjoy themselves during a vacation. A Ben-Gurion University study about the problems people with disabilities face during their hotel experience has been voted a “Highly Commended Award Winner” at the Literati Network of Emerald Publishing House Awards for Excellence 2012.
Prof. Yaniv Poria, Prof. Arie Reichel of the university’s hotel and tourism management department and Yael Brandt, a business administration graduate of the Guilford Glazer Faculty of Business and Management published their study recently in the International Journal of Contemporary Hospitality Management.
The study focuses on the challenges arising from the interactions between wheelchair users, individuals using crutches as well as blind people and the hotel environment. It also suggested ways of overcome these challenges.
As this study aims to broadcast the genuine voice of people with disabilities, a qualitative research approach was adopted. The study included in-depth interviews with 45 participants; 20 used wheelchairs, 10 were dependent on crutches and 15 were blind.
Interpreted by the social model of disability rather than by medical diagnosis methods, the results suggest that the challenges the disabled confronted come from the physical design of the environment as well as the behavior of the hotel staff. The findings indicate that participants assigned more importance to staff attitudes than to the physical environment.
The paper suggests to hotel managers specific physical as well as interpersonal means to alleviate apparent difficulties faced by people with disabilities in their hotel experiences. For example, it was found that hotel employees treat people with disabilities as if they were intellectually inferior by responding to their companion rather than directly to them. These findings, BGU says, are of great importance to the Israeli hospitality industry that is facing accessibility requirements by law.