Page 23 - Read Online

Xu et al. Radiation therapy in keloids treatment

considered as the last resort which can significantly beam irradiation and to low dose rate or high dose rate
reduce recurrence rate. [25] Notably, the definition of brachytherapy, radiation therapy technology treatment
recurrence is controversial which might cause bias has provided us with several options on different
in clinical studies. The universally accepted definition lesions and different sites. However, we still believe
was an elevation of the scar, extending beyond that the damage mechanism and the mechanism
the original surgical field. [26] Early in 1970s, several behind resistance generation are largely similar
negative results drew the determined conclusion that among all radiation therapy types. Moreover, the
simply surgical excision was accompanied with high cellular response to radiation therapy was rendered as
rate of recurrence, ranging from 40% to 100%. [27] The a possible explanation accounting for local recurrence.
possible explanation was surgery itself was considered Indeed, what role did irradiation played remained
as the stimulation of additional collagen synthesis. unclear. We now present a comprehensive review over
Therefore, the surgical excision was no longer used this issue, trying to identify the most valuable pathway
alone. The combination therapy of surgical excision involved in cellular response to irradiation.
and radiation therapy gradually replace the traditional
surgical excision. Starting from superficial X-ray POTENTIAL MOLECULAR PATHWAYS AND
irradiation, the radiation therapy effectiveness was CELLULAR RESPONSE
gradually proven. Radiation therapy has a long history
being applied in treating keloids. The inhibition of Unfortunately, no present literatures could perform a
scar growth and postoperative keloids formation was thorough review on the ways which irradiation played.
found back to early in the 20th century. DeBeurman It might be attributed to the diversity of irradiation
and Gougerot first described X-ray treatment of source and particles or uncertainty of molecular
keloids in 1906 and serial positive reports followed. [28] pathways dominance in keloid formation. A fraction
First recommended in keloids prevention and then dose of 5 Gy was considered effective in eliminating
escalated to keloids treatment. [29] Meanwhile, the rapid aberrantly activated fibroblasts and promoting the rest
technology development also contributed to extension of normal fibroblasts. [31] Similarities of direct damage
of radiation therapy application in treating keloids. From and cellular response to ionizing irradiation could bring
kilovoltage irradiation to electron beam irradiation, from us some potential inspirations. Genetic susceptibility,
outside of the body to inside of the body, the transition radiosensitivity and complications were taken into
of technology brought improvement recurrence rate our consideration. As known to us, the biological
reduction and better normal tissue sparing. As one of effectiveness of radiation was quite dependable owing
the experienced radiation therapy center, our team is to different sites, linear energy transfer (LET), total
quite familiar with this combination therapy. Actually, dose, fractionation rate and radio-sensitivity. Various
different radiation therapy facility, technology, different mechanisms were reportedly involved in killing cancer
treatment modality combined and different treatment cells or benign tumor cells. Early explanation was built
protocol will cause variable clinical outcome. For on the hypothesis that local fibroblasts which were
example, due to the radiation therapy center of our destroyed by irradiation cannot be replaced by distant
hospital, we here gave our recommendation of our fibroblasts. [32] Under light microscope, programmed
treatment modality. The first radiation therapy should cell death or apoptosis dominated in post-irradiated
be performed within 48 h postoperatively or after other targeted tissues. Apoptotic numbers and ratio in
procedures. The radiation therapy was performed 1st postoperative keloid tissues were considered as
day postoperatively and on the 8th day of hypofractions very important index evaluating the radio-sensitivity
as reported by Shen et al. [30] previously. The external and direct DNA damage. Correspondingly, necrosis,
beam was administered using 6 or 7 MeV electrons. mitotic cell death or mitotic catastrophe, senescence,
Flat lesion surface was largely achieved by patient autophagy were also observed and partially proved
position change confirmed by radiation therapists. The in some in vitro studies. [33] The intracellular target
field of irradiation field covered the entire lesion site was apparently the DNA, whose damage can cause
with 1 cm margin to ensure the enclosure the margin. irreversible cell injury or triggering the programmed
Normal tissue shielding was implemented by appliance cell death. The most effortless classification of these
of a 0.8 cm customized lead sheet. Additionally, 0.5 cm damages was naturally dividing them into two parts,
of wax was utilized to broaden the radiation field. For direct damage and indirect damage. Direct damage
every single lesion, a total dose of 18 Gy in 2 fractions essentially referred to the interaction between radiation
with interval of 1 week was well established. In a brief and DNA, while indirect damage referr to the damage
summary, the relative low ā/β ratio of lower fractions from radiation-derived free radicals. Direct actions
and higher doses were presumed as the choice of dominate in high-LET ionizing irradiation technology
treatment. Ranging from superficial X-rays, to electron- (neutrons and other heavier ions), generating high-
Plastic and Aesthetic Research ¦ Volume 4 ¦ July 28, 2017 119