Support sciences

It was found that genes useful for cancer class prediction may also provide insights into cancer pathogenesis and pharmacology
The National Cancer Institute in USA maintains a project called Human Tumor Gene Index. More than 50,000 genes active in one or more cancers have been identified; with over 6,000 genes active in breast cancer cells, 277 that are not active in other tissues

Support sciences

Interpretation of tumor data would involve an experienced hematophothologist for tumor morphology, histochemistry and immunophenotyping analysis
Histopathology is the science that studies pathologic tissues. Just as in the case of all other branches of biological sciences, bioinformatics is poised to bring monumental changes to this branch as well. It is expected that it would also greatly influence the cancer pathogenesis and pharmacology

Fighting cancer

Fighting cancer is not just hoping to discover a “magic bullet” to annihilate it
It is much broader a problem
Early detection
Curative measures
Rehabilitation of the patients
Psychological problems faced by the patient and relatives

Cancer cure is expanding…

In the 1950s, only 30 percent cancers were curable
By 1977, that percentage had risen to 41
By 1980, 45 percent of all serious cancers were curable
This percentage is increasing fast

Is cancer inherited?

There are cases of some families, several members of which have suffered from cancer
Scientists have propagated some strains or breed of mice in which a large number of males developed lung cancer and over 90 percent of females breast cancer
A careful analysis of data shows that certain types of cancer are hereditary and there is a likelihood of cancer of a particular tissue or organ developing in the descendants of persons who have suffered from cancer

How does cancer spread?

Cancer spread occurs through any or all of the three routes
Local spread: cancer infiltrates the adjoining parts, organs, tissues, etc.
Lymphatic spread: the lymph glands or nodes trap the cancer cells present in the lymph fluid and cancer grows within them. Progressive spread along lymph vessels and glands may occur and in the process quite distant glands may become involved

Bloodstream spread: if cancer invades blood vessels then the cancer cells may break into the bloodstream and be carried to other parts of the body and settle over there, producing secondary cancers. The major site of spread in cases of bowel cancer is liver. The lungs are the commonest site of metastasis from other cancer sites. The spread to many other organs is also common

Tumor

Growth of cancer cells leads generally to formation of a nodule or tumor; hence cancer is also called a tumor
If it is superficial, it is firm to touch, gets fixed to surrounding tissues and is not freely moveable
However, every nodule is not cancer
Some like warts, cysts, or adenomas are benign and are easily treated
But in order to be sure whether a nodule is cancerous, a bit of the nodule is taken and examined under the microscope, which generally gives a correct diagnosis

Fast and slow-growing cancers

A cancer may be slow- or fast-growing
The rate of growth depends on the tissue in which it occurs and also on the inherent character of the type of cancer
Rapidly growing cancers are those which send metastasis in other organs, are much more dangerous
Sometimes the primary cancer in the first stage of development grows slowly, as for example, that of the stomach and remains unnoticed, while the secondaries spread rapidly in the liver, abdominal lymph glands, etc. These secondary cancers are first noticed

Cancer cells vs. normal cells

Cancer cells are different from normal cells in some aspects
They do not remain confined to one part of the body
They penetrate and infiltrate into the adjoining tissues and dislocate their function
Some of the cancer cells get detached from the main mass or site of origin and travel by blood cell and lymph channels to sites distant from the original tumor and form fresh colonies, called metastasis or secondary growths, in other organs where they grow at the cost of the normal cells
This is how they destroy the well-regulated functioning of the body and bring about its end

Other causes of cancer

Genetic and personal factors – age, sex, race, marital status, heredity, socio-economic status
Immune deficiency
Environmental
Virus, e.g., polyoma virus causes leukemia

Physico-chemical causes of cancer

Benza pyrene (found in coal, tar, etc.)
Asbestos causes mesothelioma, cancer of the pleura
Dyes, synthetic colors
Aromatic amines, polycyclic aromatic hydrocarbons
Urethane
Metals like nickel, chromium, arsenic, beryllium
Harmones
Aflatoxin, pesticides, insecticides
Diethy stilbesterol (medicinal compound/female sex harmone)

Cancer cause

Cancer arises from the abnormal and uncontrolled division of cells, known as cancer cells, that then invade and destroy the surrounding tissues
Cancer cells, in other words, refuse to stop multiplying and continue to increase in number
It is the failure to stop multiplying which is the hallmark of cancer
This they do even at the cost of other normal cells of body which are starved to death for lack of nutrition

Cancer treatment

Cancer being more common in older people, increasing life span of man is providing more and more candidates for getting the disease
Surgery to treat it has been used since centuries ago
Radiation was used to treat breast cancer within one year of Roentgen’s discovery
World War II provided the first drug in the form of nitrogen mustard to kill cancer cells

Cancer

It has existed all along with man
Twenty-five centuries ago, Hippocrates, called it karkinois because the swollen blood vessels going and coming from the tumor mass, gave the appearance of the claws of a crab
Susruta described cancer as a tumor which would ulcerate and would not cure, and “sow its seeds in other parts of the body”

Life style drugs

Toe nail fungus
Obesity
Baldness
Face wrinkle
Erectile dysfunction
Separation anxiety of dogs, etc.

Main targets for drug design as per WHO report Jan 2002

AIDS
Tuberculosis
Malaria

Third world diseases

Asthma
Cystic fibrosis
Huntington’s disease
Sickle cell anemia
Malaria
Tuberculosis
Typhoid
HIV/AIDS
SARS

The HP virus

After breast cancer, cervical cancer kills more women each year than any other cancer
It is particularly so in developing countries, where screening is not widespread
Lasting infection from certain strains of a common sexually transmitted virus – human papilloma virus (HPV) – causes almost all cervical cancers
HPV was first linked to cervical cancer in 1983
Infection most in women of age group 16-23 years

AIDS tests have a flaw?…

The ELISA and Western Blot tests look for
the antibodies to HIV in blood
samples
But these antibodies are also found in samples
of patients whose immune systems have been
activated by several other conditions – like
tuberculosis, multiple sclerosis and even
warts
These two tests actually look for the p24 protein
which is found in healthy persons
also

Canadian team sequencing SARS virus

Scientists from the Genome Science Centre
at the British Columbia Cancer Agency are
sequencing the Severe Acute Respiratory Syndrome
(SARS) virus
30 genome researchers from 11 countries are involved
in the project
Early identification using electron microscopy,
PCR and viral microarray have identified the SARS
virus as a corona virus

DNA repair

Using yeast genome, scientists discovered the fundamental mechanism cells use to control how and when they divide
This has enlightened everyone about cell division and DNA repair, processes that are important in cancer diagnosis and control
One of the findings is that the common chemotherapeutic drug ‘cisplatin’ is particularly effective in killing cancer cells that have s specific defect in their ability to repair their DNA

The p53 protein

One of the fly genes with a human counter part is p53,
a so-called tumor suppressor gene that when mutated allows
cells to become cancerous
The p53 gene is part of a molecular pathway that
causes cells that have suffered irreparable genetic damage
to commit suicide
It was identified that just as in human cells, fly cells
in which the p53 protein is rendered inactive, lose the ability
to self-destruct after they sustain genetic damage and instead
grow uncontrollably

Some noted works

Golub, Slonim et al (1999) published a paper on
molecular classification of cancer.
This relates to their study of class discovery
and class prediction by gene expression monitoring

Slonim, Tamayo et al (2000) subsequently studied
class prediction and discovery using gene expression
data

Ramaswamy et al (2001) brought out multiclass
cancer diagnosis using tumor gene expression
signature

smaller sets are preferred for processing…

Large samples of over 200 genes are not helpful
since if all of them are correlated with a particular
class, it is unlikely that they all represent
different biological mechanisms and hence are
unlikely to add information not already provided
by others
Though excellent research work has been carried out
in last three decades, there are no general approach
for identifying new cancer classes (class discovery)
or for assigning tumors to known classes
(class prediction)

Foundations - Bioinformatics and disease link

Gene expression data analysis could give important
clues for reasons behind cause of various diseases,
especially about the behaviour and growth of disease
causing germs

Communicable diseases – malaria,
typhoid, cholera

HIV/AIDS

Cancer

Dengue

Medical informatics

Part 1 – Foundations
Part 2 – Cancer
Part 3 – Detailed Look into Cancers
Part 4 – Response of Cancers to Chemotherapy