What are recent machanism of actions, minmum duration of years of heat exposure and minimum temperature required for various heat induced skin cancers, also opnion for Kangri Cancer to be answered

Kangri cancer is a heat-induced skin carcinoma associated with the use of the Kangri. This Kangri, which is a traditional fire pot, is an ingenious mode of providing warmth. The Kangri is an earthenware container with an outer encasement of wickerwork that is filled with ignited coal inside for providing a source of heat in winter months. Its prolonged use may result in formation of erythema, a reticulate hypermelanosis with erythema, which may transform into cutaneous cancer. Currently, this skin cancer rarely is found in the Kashmir valley. Heat-induced skin cancers, notably Kangri cancer, arise from chronic thermal injury causing DNA damage, inhibiting repair mechanisms (like TP53), and promoting chronic inflammation. Key mechanisms include thermal stimulation of DNA damage, reduced apoptosis of damaged cells, and accelerated mutation rates. Chronic exposure often spans 10-40 years, while intense, intermittent exposure (e.g., in Kangri usage) can act over shorter yearly periods but long lifetimes.   In a 5-year study was conducted during which 17 patients who were documented with a Kangri cancer were treated. Sixteen patients had cancer on a thigh and 1 had cancer on the abdominal wall. All had an excision of the neoplasm. Histopathology documented squamous cell carcinoma in all patients. This study have point out that  Kangri cancer still occurs in patients who live in remote areas of Kashmir where there is a chilling cold in winter months and have no modern and alternative cheap means of warming other than the Kangri.

Long term sub burn (usually above 40-45 ° C) repeated heat stimulation can induce squamous cell carcinoma of the skin through a clear mechanism: repeated heat stress causes local DNA damage by inhibiting the DNA repair pathway (especially p53 mutations), while also triggering chronic inflammation, oxidative stress, and pro angiogenic cytokines, and leading to local immune suppression by reducing Langerhans cells. For most heat induced skin cancers, including Kangri cancer (Kashmir), Kairo cancer (Japan), and malignant transformation secondary to fire erythema, the minimum exposure period is usually 10 to 30 years, and the key temperature threshold is continuous repeated exposure to heat sources above 43 ° C. Kangri cancer is a typical representative of this process: patients who have kept Kangri (pottery brazier) under clothing for many years to keep warm first develop fiery erythema in their abdomen and inner thighs. After 20-30 years, it progresses to well differentiated squamous cell carcinoma, which follows the triple pathogenic pathway of heat induced DNA damage, chronic inflammation, and immune evasion. Although it is currently difficult to establish a unified absolute minimum carcinogenic temperature, any long-term, repeated, localized heat exposure exceeding 43 ° C, accumulated over many years, carries a clear risk of cancer. The key to prevention is to interrupt continuous exposure and increase insulation protection.

The effects of heat on skin cancer include DNA damage due to elevated temperatures. Ultraviolet (UV) radiation further exacerbates DNA damage, promoting cancerous mutations and leading to chronic inflammation. This, in turn, increases the production of heat shock proteins, which may help cancer cells survive instead of dying. Reducing sun exposure involves avoiding direct sunlight (especially between 10 a.m. and 4 p.m.), as it raises the skin's surface temperature and causes cumulative damage. Intense summer heat increases the likelihood of death from skin cancer. Research suggests that the minimum temperature required for heat therapy should be between 40 and 45 degrees Celsius. Medical treatment for skin cancer includes several methods, such as traditional surgery (excision), Mohs microsurgery for basal cell and squamous cell carcinomas, cryotherapy (liquid nitrogen), or heat therapy to destroy tumors using high-intensity heat or laser treatment. These methods can lead to serious health problems, including a weakened immune system. Among the most important preventive measures are: avoiding exposure to sunlight during peak hours (from 10 a.m. to 4 p.m.), regular use of sunscreen, and wearing protective clothing and hats.