Tumors and Cancers

Skin – Soft Tissue – Bone – Urogenitals

Dongyou Liu

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781351646871
• Edition: 1
• Topic: Medicine
• Subtopic: Oncology

Tumors and Cancers: Skin – Soft Tissue – Bone – Urogenitals provides succinct reviews of neoplastic growths disrupting normal functions of affected structures. Each chapter presents a state of the art summary of tumor/cancer of a particular type in relation to its biology, epidemiology, disease mechanisms, clinical signs, diagnosis, treatment and prognosis.

1

Introductory Remarks

1.1 Preamble

Tumor or cancer (these terms, along with neoplasm and lesion, are used interchangeably in colloquial language and publications; see the glossary) is an insidious disease that results from an uncontrolled growth of abnormal cells in parts of the body. Tumor or cancer has acquired a notorious reputation not only due to its ability to exploit host cellular machineries for its own advantages but also due to its potential to cause human misery.

With a rapidly aging world population, widespread oncogenic viruses, and constant environmental pollution and destruction, tumor or cancer is poised to exert an increasingly severe toll on human health and well-being. There is a burgeoning interest from health professionals and the general public in learning about tumor and cancer mechanisms, clinical features, diagnosis, treatment, and prognosis. The following pages in this volume, as well as those in sister volumes, represent a concerted effort to satisfy this critical need.

1.2 Tumor mechanisms

The human body is composed of various types of cells that grow, divide, and die in an orderly fashion (so-called apoptosis). However, when some cells in the body change their growth patterns and fail to undergo apoptosis, they often produce a solid tumor and sometimes a nonsolid tumor (as in the blood). A tumor is considered benign if it grows but does not spread beyond the immediate area in which it arises. While most benign tumors are not life-threatening, those found in the vital organs (e.g., brain) can be deadly. In addition, some benign tumors are precancerous, with the propensity to become cancer if left untreated. On the other hand, a tumor is considered malignant and cancerous if it grows continuously and spreads to surrounding areas and other parts of the body through the blood or lymph system.

A tumor located in its original (primary) site is known as a “primary tumor.” A tumor that spreads from its original (primary) site via the neighboring tissue, bloodstream, or lymphatic system to another site of the body is called “metastatic tumor or cancer” (or secondary tumor or cancer). A metastatic cancer has the same name and same type of cancer cells as the primary cancer. For instance, a metastatic cancer in the brain that originates from breast cancer is known as metastatic breast cancer, not brain cancer.

Typically, a tumor or cancer forms in tissues after the cells undergo genetic mutations that lead to abnormal changes known as hyperplasia, metaplasia, dysplasia, neoplasia, and anaplasia (see the glossary). Factors contributing to genetic mutations in the cells may be chemical (e.g., cigarette smoking, asbestos, paint, dye, bitumen, mineral oil, nickel, arsenic, aflatoxin, wood dust), physical (e.g., sun, heat, radiation, chronic trauma), viral (e.g., EBV, HBV, HPV, HTLV-1), immunological (e.g., AIDS, transplantation), endocrine (e.g., excessive endogenous or exogenous hormones), or hereditary (e.g., familial inherited disorders).

In essence, tumorigenesis is a cumulative process that demonstrates several notable hallmarks, including (1) sustaining proliferative signaling, (2) activating local invasion and metastasis, (3) resisting apoptosis and enabling replicative immortality, (4) inducing angiogenesis and inflammation, (5) evading immune destruction, (6) deregulating cellular energetics, and (7) genome instability and mutation.

1.3 Tumor classification, grading, and staging

Tumor or cancer is usually named for the organs or tissues from where it starts (e.g., brain cancer, breast cancer, lung cancer, lymphoma, and skin cancer). Depending on the types of tissue involved, a tumor or cancer is grouped into a number of broad categories: (1) carcinoma (involving the epithelium), (2) sarcoma (involving soft tissue), (3) leukemia (involving blood-forming tissue), (4) lymphoma (involving lymphocytes), (5) myeloma (involving plasma cells), (6) melanoma (involving melanocytes), (7) central nervous system cancer (involving the brain or spinal cord), (8) germ cell tumor (involving cells that give rise to sperm or eggs), (9) neuroendocrine tumor (involving hormone-releasing cells), and (10) carcinoid tumor (a variant of a neuroendocrine tumor found mainly in the intestinal tract).

Primary tumors of the skin encompass those affecting the keratinocytes, melanocytes, epithelial adnexal tissue (e.g., sweat glands), hematolymphoid tissue, soft tissue, and neural tissue (peripheral or autonomic nerves), in addition to inherited tumor syndromes [1].

Primary tumors of soft tissues comprise adipocytic tumors, fibroblastic or myofibroblastic tumors, so-called fibrohistiocytic tumors, smooth muscle tumors, pericytic or perivascular tumors, skeletal muscle tumors, vascular tumors, chondro-osseous tumors, gastrointestinal stromal tumors, nerve sheath tumors, tumors of uncertain differentiation, undifferentiated or unclassified sarcomas, and congenital and inherited tumor syndromes [2].

Primary tumors of the bone range from cartilage tumors, osteogenic tumors, fibrogenic tumors, fibrohistiocytic tumors, Ewing sarcoma or primitive neuroectodermal tumors, hematopoietic tumors, giant cell tumors, notochordal tumors, vascular tumors, smooth muscle tumors, lipogenic tumors, neural tumors, miscellaneous tumors, miscellaneous lesions, and joint lesions, to congenital and inherited tumor syndromes [2].

Primary tumors affecting the urinary tract are separated into urothelial tumors, squamous neoplasms, glandular neoplasms, neuroendocrine tumors, melanocytic tumors, mesenchymal tumors, hematopoietic and lymphoid tumors, and miscellaneous tumors [3]. Primary tumors of the male genital organs include those affecting the prostate, testis, paratesticular tissue, and penis [3]. Primary tumors of the female genital organs comprise those affecting the ovary, peritoneum, fallopian tube, uterine ligaments, uterine corpus, uterine cervix, vagina, and vulva, as well as inherited tumor syndromes [4].

Primary tumors of the breast consist of epithelial tumors, myoepithelial lesions, mesenchymal tumors, fibroepithelial tumors, tumors of the nipple, malignant lymphoma, metastatic tumors, and tumors of the male breast [5].

Under the auspices of the World Health Organization (WHO), the International Classification of Diseases for Oncology, Third Edition (ICD-O-3) [6] has designed a five-digit system to classify tumors, with the first four digits being morphology code and the fifth digit behavior code [6]. The fifth-digit behavior codes for neoplasms are 0, benign; 1, benign or malignant; 2, carcinoma in situ; 3, malignant, primary site; 6, malignant, metastatic site; and 9, malignant, primary or metastatic site. For example, chondroma has an IDC-O code of 9220/0 and is considered a benign bone tumor; multiple chondromatosis (a subtype of chondroma) has an IDC-O code of 9220/1 and is an intermediate-grade bone tumor with the potential for malignant transformation; and central chondrosarcoma has an IDC-O code of 9220/3 and is considered a malignant bone tumor [2, 6].

To further delineate tumors and cancers and assist their treatment and prognosis, the pathological stages of solid tumors are often determined by using the TNM system of the American Joint Commission on Cancer (AJCC), which incorporates the size and extent of the primary tumor (TX, T0, T1, T2, T3, and T4), the number of nearby lymph nodes involved (NX, N0, N1, N2, and N3), and the presence of distant metastasis (MX, M0, and M1) [7]. Therefore, the pathological stage of a given tumor or cancer is referred to as T1N0MX or T3N1M0 (with numbers after each letter providing further details about the tumor or cancer). However, a much simplified clinical stage (0, I, II, III, and IV), which is based on results of clinical exam and various tests in the absence of findings during surgery, is used routinely to guide the treatment of solid tumors (see stage and TNM in the glossary) [7].

Another staging system that is more often used by cancer registries than by doctors divides tumors and cancers into five categories: (1) in situ (abnormal cells are present but have not spread to nearby tissue), (2) localized (cancer is limited to the place where it started, with no sign that it has spread), (3) regional (cancer has spread to nearby lymph nodes, tissues, or organs), (4) distant (cancer has spread to distant parts of the body), and (5) unknown (there is not enough information to figure out the stage).

1.4 Tumor diagnosis

As most tumors and cancers tend to induce nonspecific, noncharacteristic clinical signs, a variety of procedures and tests are employed during diagnostic workup. These involve a medical history review of the patient and relatives (for clues to potential risk factors that enhance cancer development), a complete physiological examination (for lumps and other abnormalities), imaging techniques (e.g., ultrasound, computerized tomography [CT], MRI, and positron emission tomography [PET]; see the glossary), biochemical and immunological tests (for altered substance or cell levels in blood, bone marrow, cerebrospinal fluid, urine and tissue), histological evaluation of the biopsy and tissue (using hematoxylin and eosin [H&E], immunohistochemical [IHC] stains, etc.; see the glossary), and laboratory analysis (e.g., fluorescence in situ hybridization [FISH] and polymerase chain reaction [PCR]; see the glossary).

1.5 Tumor treatment and prognosis

Standard cancer treatments consist of surgery (for removal of the tumor and relieving symptoms associated with the tumor), radiotherapy (also called radiation therapy or X-ray therapy; delivered externally through the skin or internally [brachytherapy] for destruction of cancer cells or impeding their growth), chemotherapy (for inhibiting the growth of cancer cells, suppressing the body’s hormone production or blocking the effect of the hormone on cancer cells, etc.; usually via the bloodstream or oral ingestion), and complementary therapies (for enhancing patients’ quality of life and improving well-being). Depending on the circumstances, surgery may be used in combination with radiotherapy and/or chemotherapy to ensure that any cancer cells remaining in the body are eliminated.

The outcomes of tumor or cancer treatments include (1) cure (no traces of cancer remain after treatment and cancer will never come back), (2) remission (signs and symptoms of cancer are reduced; in a complete remission, all signs and symptoms of cancer disappearing for 5 years or more suggests a cure), and (3) recurrence (a benign or cancerous tumor comes back after surgical removal and adjunctive therapy).

Prognosis (or chance of recovery) for a given tumor is usually dependent on the location, type, and grade of the tumor; patient’s age and health status, etc. Regardless of tumor or cancer types, patients with lower grade lesions generally have a better prognosis than those with higher grade lesions.

1.6 Future perspective

Tumor or cancer is a biologically complex disease that is expected to surpass heart disease to become the leading cause of human death throughout the world in the coming decades. Despite extensive past research and development efforts, tumor or cancer remains poorly understood and effective cures remain largely elusive.

The completion of the Human Genome Project in 2003 and the establishment of The Cancer Genome Atlas (TCGA) in 2005 have offered promises for better understanding of the genetic basis of human tumors and cancers, and opened new avenues for developing novel diagnostic techniques and effective therapeutic measures.

Nonetheless, a multitude of factors pose continuing challenges for the ultimate conquering of tumors and cancers. These include the inherent biological complexity and heterogeneity of tumor or cancer, the contribution of various genetic and environmental risk factors, the absence of suitable models for human tumors and cancers, and difficulty in identifying therapeutic compounds that kill or inhibit cancer cells only and not normal cells. Further effort will be necessary to help overcome these obstacles, and enhance the well-being of cancer sufferers.

Acknowledgments

Credits are due to a group of international oncologists/clinicians, whose expert contributions have greatly enriched this volume.

References

1. LeBoit PE, Burg G, Weedon D, Sarasin A. Pathology and Genetics of Skin Tumours. International Agency for Research on Cancer (IARC). Lyon, France: IARC Press, 2006.

2. Fletcher CDM, Bridge JA, Hogendoorn P, et al. (eds.). WHO Classification of Tumours of Soft Tissue and Bone. 4th ed. Lyon, France: IARC Press, 2013.

3. Eble JN (e...

Table of contents

• Title Page
• Copyright Page
• Table of Contents
• Series Preface
• Contributors
• 1 Introductory Remarks
• Section I: Skin, Soft Tissue, and Bone
• Section II: Urogenitory System
• Glossary
• Index