Aging And Oncogenesis

Advancing age has been described as the most potent of all carcinogens.16 In humans, the incidence of cancer rises exponentially in the final decades of life, culminating in a lifetime risk of 1 in 2 for men and 1 in 3 for women.17 This dramatic escalation in the incidence of cancer among the aged is largely due to epithelial carcinomas that develop between ages 40 and 80. Until recently, the most common explanation for the increased incidence of cancer among older people has been the...

New Developments In Imaging

A large number of new imaging techniques have developed since the advent of CT, MRI, and ultra-sonography. Some developments are essentially improvements of established techniques, such as spiral CT, which offers faster acquisition, lower exposure to ionizing radiation, and higher resolution than conventional CT. Especially in the MRI field, there has been a constant search for better and faster imaging algorithms and stronger magnetic fields to decrease noise and increase resolution. MRI...

Tumor Suppressor Genes

In 1971, while researchers were still identifying new members of the family of oncogenes, Alfred G. Knud- Growth factors or receptors for growth factors PDGF platelet-derived growth factor (brain and breast cancer) erb-B receptor for epidermal growth factor (brain and breast cancer) erb-B2 receptor for growth factor (breast, salivary, and ovarian cancers) RET growth factor receptor (thyroid cancer) Cytoplasmic relays in stimulatory signaling Kras activated by active growth factor receptor...

Conclusions

The incidence of disease processes of the orbit and ocular adnexa, both infective and neoplastic, has changed over time and varies enormously in geographic distribution. These trends have been largely due to changes in the incidence of infections with some bacteria and viruses. In addition, our understanding of the role of infectious agents in the development of neoplasms has increased, and it is likely that their role is greater than had been recognized in a large number of orbital and ocular...

Types Of Second Malignancy

The most common SMN, osteogenic sarcoma (Figures 5.2 and Figure 5.3), occurs at about the same age as in the normal population, around the second decade.42-44 The frequency of bone and soft tissue sarcomas is not surprising, since many of these tumors seem to harbor Rb-I mutations.45,46 The osteogenic sarcoma incidence in the literature varies from 19 to 54 of all FIGURE 5.5. Extensive esthesioneuroblastoma developed in the left orbit and nasal cavity following enucleation and postoperative...

Primary Orbital Lesions

Dumbbell Dermoid

Epithelial and Dermoid Cysts The most common developmental cysts occurring in the orbital and periorbital region and having a predilection for the superotemporal quadrant, are the epithelial and dermoid cysts. Dermoid cysts contain one or more epidermal appendages such as hair follicles, sweat glands, and sebaceous glands epithelial cysts contain only stratified squamous cell epithelium. Echographi-cally, epithelial and dermoid cysts appear on B scans as smoothly rounded, echolucent lesions...

Well Circumscribed Cystic Lesions

The most common clinical differential diagnosis of cystic orbital lesions includes dermoid cyst, colobo-matous cyst, teratoma, meningoencephalocele, lymphangioma, acquired inclusion cyst, chronic hematic cyst (cholesterol granuloma), mucocele, subperiosteal hematoma, and parasitic cyst.25 On MRI these lesions appear as well-defined, round to oval lesions with variable signal intensity depending on the composition of their content (Table 10.4).1,2,5,31 Dermoid cyst may have an homogeneous or...

Fibrous Dysplasia

Fibrous dysplasia is a benign developmental disorder of the bone that results from the arrest in the maturation of primitive woven bone into mature lamellar bone containing osteoblasts.57 It can be considered to be a hamartomatous disorder. In fibrous dysplasia os-teoblastic activity is arrested and the mature lamellar bone is not formed.57 The anomaly is considered to be the result of a specific mutation of the Gs alpha gene.58 In approximately 75 of cases, the disease involves only one bone...

Immunosuppression And Cancer

Perhaps the greatest change in the nature and frequency of some orbital disorders has been in those that occur more frequently in the immunosuppressed patient. The treatment of many disorders, especially for those of an autoimmune type and for the immuno-suppression required for solid organ transplants, has involved general suppression of the immune system at the expense of an increased risk and incidence of formerly rare disorders. Immunodeficiency may be congenital, therapeutic, or infectious...

Ionizing Radiation Chemicals And Cancer

The carcinogenic potential of ionizing radiation was soon recognized after Roentgen's discovery of x-rays in December 1895. The first report of leukemia in five radiation workers dates back to 1911.43 (Marie Curie and her daughter, Irene, are both thought to have died from complications of radiation-induced leukemia.) Follow-up studies on atomic bomb survivors in Hiroshima and Nagasaki have confirmed that ionizing radiation is a universal carcinogen in that it induces tumors in most tissues of...

Gene Overexpression And Downregulation

Invasiveness and metastatic ability of the neoplastic cells appear as a result of accumulation of newly acquired genetic alterations beyond those that initiate oncogenesis.7 Some of these alterations may include more than a few genes.8 Mutations occur at a higher rate in cancer cells because their genetic material (chromosomes or DNA) is intrinsically unstable.17 This genetic instability seems to be a property of cancer cells. Abnormalities (i.e., loss or gain of chromosomal material) are...

Ocular Examination

Juxtapapillary Hemangioma

The ocular examination should include the best corrected visual acuity and intraocular pressure applana-tion in the primary position and in different vertical and horizontal gazes. A neuro-ophthalmologic examination, including motor and sensory functions, pupillary examination, contrast sensitivity, color vision assessment, confrontation visual fields, and central visual acuity with an Amsler grid should also be done (see Chapter 7). During biomicroscopy, the integrity of the corneal and...

Viruses And Oncogenesis

In Chapter 1, we pointed out the role that viruses have historically played in our understanding of the molecular bases of cancer. Viruses have been defined as the Rosetta Stone for unlocking the mysteries of cell growth control. They have also revealed the functional foundations of the genetic bases of cancer and provided a conceptual framework applicable to all can-cers.34 The concept that viruses cause cancer dates back to the first decade of the twentieth century, when Francis Peyton Rous...

Role Of Ebrt In Second Malignancies

There is general agreement that radiotherapy increases the incidence of SMNs in patients with Rb.24,61-64 The only large study reporting that the SMN incidence was independent of radiation therapy was that of DeSut-ter and coworkers.40 Radiation-induced tumors of the eye are classified as those that arise within the field of radiation (i.e., eyelids, orbit, periorbital sinuses, skin, and subcutaneous tissues overlying the periorbital area). In the study of Roarty and coworkers, the 30-year...

Orbital Examination

Optic Disc Haemorrhage

The external examination of the patient should assess the facial features and critically evaluate the symmetry of the ocular, eyelid, and orbital structures. Phys ical examination of the periorbital structures, including eyelids and conjunctiva, should include inspection of appearance and function, which are commonly altered by a space-occupying lesion in the orbit. The horizontal distance between interpalpebral fissures and the width of the palpebral fissures should be measured and recorded....

Immunological Response To Cancer

Orbital Tumor

For the immune system to react against a tumor, tumor cells must express antigens that are recognized to be foreign by the individual's immune system. As outlined in Chapter 1, structural alterations of chro mosomes (i.e., aneuploidy) typical of cancerous transformation lead to complex cancer-specific phenotypes, including abnormal cellular and nuclear morphology, metabolism, growth, DNA indices, invasiveness, metastasis, and neoantigens.5,6 Neoantigens are usually subdivided into two major...

Do Mutations Matter In Cancer

For nearly a century cancer has been blamed on somatic mutation. As we have seen, one of the fundamental distinctions between oncogenes and TSGs is based on the assumption that a single mutation involving one allelic copy of an oncogene (cancer dominant gene) or two sequential mutations involving both copies of a TSG (cancer recessive gene), are sufficient to determine cancer. However, it has been shown that many, if not all of the predictions made by the somatic mutation model, as applied to...