A precancerous condition is a condition, tumor or lesion involving abnormal cells which are associated with an increased risk of developing into cancer. Clinically, precancerous conditions encompass a variety of abnormal tissues with an increased risk of developing into cancer. Some of the most common precancerous conditions include certain colon polyps, which can progress into colon cancer, monoclonal gammopathy of undetermined significance, which can progress into multiple myeloma or myelodysplastic syndrome, and cervical dysplasia, which can progress into cervical cancer. Bronchial premalignant lesions can progress to squamous cell carcinoma of the lung.

Pathologically, precancerous tissue can range from benign neoplasias, which are tumors which don't invade neighboring normal tissues or spread to distant organs, to dysplasia, while precancerous conditions of the hematological system are typically asymptomatic, and in the case of monoclonal gammopathy of unknown significance, it may only rarely cause numbness and tingling in the hands and feet or difficulty with balance (see: peripheral neuropathy).

Causes

In most cases, many risk factors for precancerous conditions and lesions are the same risk factors that determines individuals vulnerable to a specific cancer. For example, individuals with cervical or anal infection with oncogenic, or cancer causing, strains of the human papilloma virus (HPV) are at higher risk for cervical and anal cancers, as well as for cervical and anal dysplasia. as well as skin cancer. Smoking is a risk factor for premalignant (as well as malignant) lung lesions. Hereditary conditions that are risk factors to cancer can also be risk factors to premalignant lesions. However, in many cases, precancerous conditions or lesions can be sporadic and idiopathic in nature, meaning that they are not associated with a hereditary genetic risk factor to the particular cancer, nor with a direct causative agent or other identifiable cause.

Pathophysiology

thumb|Stepwise progression from normal tissue to precancerous lesion to invasive cancer

The pathophysiology of precancerous lesions is thought to be similar to that of cancer, and also varies depending on the disease site and type of lesion. It is thought that cancer is always preceded by a clinically silent premalignant phase during which many oncogenic genetic and epigenetic alterations accumulate before it is truly malignant. The duration of this premalignant phase can vary from cancer to cancer, disease site to site and from individual to individual. and that the nature of the first immune response to these lesions may determine if they progress to cancer or regress to normal tissue.

Examples

Skin

  • actinic keratosis
  • Bowen's disease (intraepidermal carcinoma/squamous carcinoma in situ)
  • dyskeratosis congenita

Breast

  • ductal carcinoma in situ
  • lobular carcinoma in situ
  • Sclerosing adenosis
  • Small duct papilloma

Head and neck/oral

  • oral submucous fibrosis
  • erythroplakia
  • lichen planus (oral)
  • leukoplakia
  • proliferative verrucous leukoplakia

Gastrointestinal

  • Barrett's esophagus
  • atrophic gastritis
  • colon polyp
  • Plummer-Vinson syndrome (sideropenic dysphagia)
  • anal dysplasia (also see: anal cancer)
  • lichen sclerosus
  • Bowen's disease (penile or vulvar)
  • erythroplasia of Queyrat

Hematological

  • monoclonal gammopathy of unknown significance

References

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