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Introduction
Incidence of Cancer
What causes Cancer?
How is Cancer managed?
Importance of Screening
Immunohistochemistry, Biochemistry and tumour markers
Cancer Treatment
Surgery for Cancer
Chemotherapy for Cancer
Radiotherapy for Cancer
Palliative care
Introduction
Cancer is a preventable disease. Cancer cure is a reality if detected early. To
offer a better choice of treatment to the patients, it is important that
patients are screened, educated to identify the signs of cancer and are
assisted to seek medical attention at the earliest.
Oncology is derived from the greek words onkos (Mass, tumour) and logos (study)
which best describes the study of malignant disease. Tumours may be either
benign or malignant. The term “Cancer” usually is referred to a tumour when
there is an uncontrolled growth and spread of cells which may affect almost any
tissue of the body. Cancer is not just one disease but is a group of more than
100 different and distinctive diseases which is not contagious.
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Incidence of Cancer:
In the world, lung, colorectal and stomach cancer are among the five most
common cancers in the world for both men and women. While lung and stomach
cancer are the most common cancers worldwide in men, breast and cervical cancer
are in women. Among the non communicable diseases, the burden of cancer is
increasing. The estimated number of new cases each year is expected to rise
from 10 million in 2000 to 15 million by 2020. Some 60% of all these new cases
will occur in the less developed parts of the world. Cancer is currently the
cause of 12% of all deaths worldwide. In approximately 20 years time, the
number of cancer deaths annually will increase from about 6 million to 10
million. The principal factors contributing to this projected increase are the
increasing proportion of elderly people in the world (in whom cancer occurs
more frequently than in the young), an overall decrease in deaths from
communicable diseases, the decline in some countries in mortality from
cardiovascular diseases, and the rising incidence of certain forms of cancer,
notably lung cancer resulting from tobacco use. Approximately 20 million people
are alive with cancer at present; by 2020 there will probably be more than 30
million.
Despite cancer rates in India being lower than those seen in Western countries,
it is important to recognize that the incidence is on a rise. Increasing
migration of rural population to the cities, increase in life expectancy and
changes in lifestyles may be the cause. In India, rates for oral and
oesophageal cancers are some of the highest in the world. In contrast, the
rates for colorectal, prostate, and lung cancers are one of the lowest. There
is a significant variation with age, sex and geography in the incidence of the
various types. Risk factors of cancer is also associated with social and
economic status. Cancer risk like cervical cancer are highest in groups with
the least education. In addition, patients in the lower social classes have
consistently poorer survival rates than those in the higher social classes.
Lifestyle changes in dietary patterns and tobacco use; occupational exposure to
carcinogens and biological factors such as viral hepatitis B infection and
human papilloma virus infection also may lead to cancer development.
What causes Cancer?
Cancer begins as a mutation in the DNA of a cell as a consequence of exposure
of individuals to carcinogenic agents. This mutation results in failure of
mechanisms that regulate normal cell growth, proliferation and cell death. The
outcome of this is a tumour. Ultimately, the progress of the resulting tumour
from mild to severe abnormality, with invasion of neighbouring tissues or
distant dissemination which is also known as Metastases results in “Cancer”.
How is Cancer managed?
The first and most important step in cancer management is diagnosing the
condition. Suspicion of cancer is based in the clinical assessment which then
leads to performance of appropriate further tests. A firm diagnosis is always
made after a histopathological examination of the abnormal tissue. The other
sequence of tests include routine and specialized diagnostic investigations
like endoscopies, cytology, hormonal tests, biomarker studies and imaging
(X-ray to PET CT).
Importance of Screening:
Screening of normal people is done to detect cancer in its early stage and to
reduce mortality. Various screening tests are available which are simple and
easy. Mammography, cervical smears, endoscopies, examination of faeces for
occult blood, serum prostate specific antigen and sigmoidoscopies are some of
the routinely done tests.
Immunohistochemistry, Biochemistry and tumour markers:
Immunohistochemistry is part of pathological investigations using antibodies,
various intracellular and cellular surface proteins to determine tissue origin
of a very undifferentiated tumour, identifying subtypes of common cancers and
establishing the presence of oestrogen receptors in breast cancer.
Some of the tumours secrete proteins into blood circulations, which are
detected by routine tests of biochemistry. Few of which are unique to a tumour
(Eg. CEA, CA 125, Alfafetoproteins), LDH, HCG). Using tumour markers, one can
assess the response to treatment and check for recurrence.
Cancer Treatment:
The goals of cancer treatment are early detection, cure and improvement of the
quality of life. Care of cancer patients typically starts with recognition of
an abnormality, followed by consultation at a health care facility with
appropriate services for diagnosis Once diagnosis is made, it is important to
ascertain cancer staging, which support identifying the choice of therapy,
prognostication, and to standardize the design of research treatment protocols.
Optimal treatment of people diagnosed with certain types of cancer detected
early, for example, cancers of the uterine cervix and corpus, breast, testis,
and melanoma, will result in 5-year survival rates of 75% or more. By contrast,
survival rates in patients with cancer of the pancreas, liver, stomach, and
lung are generally less than 15%. Some treatments require sophisticated
technology that is available only in locations with substantial resources.
Treatment may involve surgery, radiation therapy, chemotherapy, hormonal
therapy, or some combination of these. Although surgery is the oldest form of
treatment, recently non-surgical role is gaining importance.
Surgery for Cancer:
The role of surgery is to remove localized tumour completely or reduce the size
of large tumour to increase the effectiveness of follow-up treatment by
radiation or chemotherapy. Surgery has a dual role, it can be done as a
diagnostic (staging) procedure as well as a curative treatment, and these two
may take place simultaneously.
In addition to curative surgery, surgery may also be performed as a preventive
measure (to remove precancerous conditions) and/or a palliative measure (to
reduce pain and other symptoms). If curative surgical procedures cause any
disfigurement or deformity, reconstructive surgery may be done to repair the
damage.
Chemotherapy for Cancer:
Unlike olden days where chemotherapy meant taking any medicine, it is now
narrowed to medications to treat cancer. Most chemotherapy drugs are given in
the form of tablets, daycare medications as in a vaccine or sometimes given
through the blood vessels through intravenous injections in the hospital.
Chemotherapy maybe given as once a day, once a week, or even once a month,
based on the type of cancer and the chemotherapy regimen that is ideal for the
condition. It is given as long as the regular follow up investigations confirm
best treatment results.
Chemotherapy uses cytotoxic treatments which is based on the propensity of
cells to die when their DNA is damaged by therapeutic means; hormonal
approaches where reducing the circulating hormones reduces the proliferation of
some tissues; and other immunological therapies which alters the natural
history of malignancy by using a profound stimulus to the immune system like
the Monoclonal antibodies.
Radiotherapy for Cancer:
The use of high-energy rays to damage cancer cells and stop them from growing
and dividing is the principle used in radiotherapy. It is a local treatment
which affects cancer cells only in the treated area by a machine externally or
from an implant placed directly into or near the tumor. Some patients receive
both kinds of radiation therapy.
Radiation therapy has been in use for the treatment of cancer and other
diseases for approximately 100 years. From the time radiotherapy moved into
clinical routine, it has undergone several changes to produce numerous
developments like generation of higher energy radiation beams for more
effective cancer treatment to the development of versatile linear accelerator
and patient table designs to enable radiation to be delivered to the cancer
from a variety of angles and directions. The implementation of "multi-leaf"
collimators (lead shutters) and other beam shaping devices for precision
control and shaping of the radiation beam and the use of Computerised
tomography (CT), Postron Emission Tomography (PET), Magnetic resonance imaging
(MR) and other image data sets to create three-dimensional planning models to
accurately guide treatment. With the use of advanced technology the
implementation of networked computers to track radiation treatment sessions and
patient dose calculations (both planned and accumulated). The final aim of all
the above changes, developments and improvements is the effective destruction
of cancer tissue while delivering a minimal dose of radiation to adjacent
healthy tissues. This has also made treatment easier and shorter for the
patient to sustain and the physicians and other healthcare professionals to
perform.
Palliative care
Palliative care is an approach that improves the quality of life of patients
and their families facing the problems associated with life-threatening
illness, through the prevention and relief of suffering by means of early
identification and impeccable assessment and treatment of pain and other
problems like physical, psychosocial and spiritual. Improved quality of life is
of paramount importance to patients with cancer.
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