Cervical cancer is among the most common types of cancer diagnosed in women around the world. Pap smear screening, which enables early detection, has played a key role in reducing the incidence of this malignancy in Europe and North America as well as some Asian countries. Nearly 90% of all deaths caused by cervical cancer occur in developing countries, mostly due to a lack of access to prevention, screening, and treatment.
On the other hand, steadily rising incidence and mortality rates for one major type of cervical cancer (cervical adenocarcinoma) have been reported in North America, the United Kingdom, Iceland, Sweden, England, Spain, Finland, Slovakia, Slovenia, and the Netherlands—with these rates being most pronounced among younger women.
Cervical cancer develops in the interior lining of the cervix and is typically slow, occurring over a period of years. The disease starts with precancerous changes in normal cells that can be relatively easy to detect. For this reason, the disease can often be diagnosed and treated at a very early stage, well before it has developed into a potentially deadly, invasive cancer.
The use of photodynamic therapy (PDT) could be especially helpful in these early-stage situations, as well as for the precancerous stage, known as cervical intraepithelial neoplasia (CIN). The latter condition poses an increased risk of developing into invasive cervical cancer. Younger women with early-stage cervical cancer will typically undergo a procedure called vaginal radical trachelectomy (VRT) iin order to preserve their ability to bear children. There have been concerns, however, that VRT may be too radical for early-stage cervical cancer, due to the high percentage of preterm births that are seen following the procedure.
A study at CHA University’s Bundang Medical Center in Gyeonggi-do, Korea, focused on the use of PDT as a less radical fertility-preserving treatment alternative to VRT. In this study, PDT was combined with either conization or the Loop electrosurgical excision procedure (LEEP). Conization entails removal of a larger area of the cervix in the shape of a cone. LEEP involves the use of a thin, low-voltage electrified wire loop to cut out abnormal tissue in the cervix.
The Korean researchers analyzed data from 21 patients with early-stage cervical cancer who underwent PDT with either LEEP or conization. Surface illumination with red laser light was applied to the cervix and the endocervical canal 48 hours after intravenous injection of a photosensitizer. After nearly five years of observation, there was one cancer recurrence and none of the women had died.
Of the 13 individuals who attempted to get pregnant, 10 (77%) women conceived a total of 11 pregnancies. Thus the authors suggest that PDT combined with LEEP/conization could be an effective fertility-sparing conservative treatment for young patients with early-stage cervical cancer, as reported ahead-of-print in the 10 June 2014 issue of Photodiagnosis & Photodynamic Therapy.
A previous study by the same research team sought to evaluate the response and efficacy of PDT to preserve fertility in young patients with high-grade CIN. Among a total of 53 patients who received PDT for CIN II/III and who wished to preserve fertility, the complete remission rate was 98% (52/53) after one year. The remaining one patient had recurred at the one-year mark.
Prior to treatment, the human papilloma virus (HPV) infection rate was 96%, but the infection had disappeared in 90% and 87% at three and 12 months (respectively) following completion of PDT. Among those 29 women in the study who tried to get pregnant, 18 patients achieved total of 25 pregnancies. Thus, in this study, PDT combined with or without LEEP/conization may be considered an effective alternative for conservative treatment of CIN in young women who wish to preserve fertility, as reported in the November 2013 issue of Lasers in Surgery and Medicine.
Finally, a recent study out of the University of Waterloo (Canada) examined the possibility of using one- and two-photon activated PDT, as this has the potential of treating deeper tumors or improving tumor targeting. Using a second-generation photosensitizer derived from chlorophyll a, the researchers found that laser-pulsed, one-photon PDT had a high degree of efficacy against cisplatin-sensitive human cervical cancer cells. The authors concluded that one-photon PDT has potential applications for tumors that are difficult to treat with conventional therapies, as reported in the 5 March 2014 Journal of Photochemistry & Photobiology.
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Choi MC, Jung SG, Park H, Lee SY, Lee C, Hwang YY, Kim SJ. Fertility Preservation by Photodynamic Therapy Combined with Conization in Young Patients with Early Stage Cervical Cancer: A Pilot Study. Photodiagnosis Photodyn Ther. 2014 Jun 10. [Epub ahead of print]
Choi MC1, Jung SG, Park H, Lee SY, Lee C, Hwang YY, Kim SJ. Photodynamic therapy for management of cervical intraepithelial neoplasia II and III in young patients and obstetric outcomes. Lasers Surg Med. 2013 Nov;45(9):564-72.
Luo T, Wilson BC, Lu QB. Evaluation of one- and two-photon activated photodynamic therapy with pyropheophorbide-a methyl ester in human cervical, lung and ovarian cancer cells. J Photochem Photobiol B. 2014 Mar 5;132:102-10.
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