Radiation-induced carcinoma of the rectum

Insight into mucinous colorectal carcinoma: clues from etiology

The prognostic impact of mucinous carcinoma (MC) in colorectal cancer (CRC) has been subject to debate ever since the introduction of the classification of tumors according to their histological differentiation. MC is a distinct clinical and pathological entity within the spectrum of CRC and accounts for approximately 10-15 % of cases. Factors involved in MC development have not been completely understood, but clinical observations may lead to a better insight into the etiology of MC. In this article, we provide an in-depth review of the literature regarding etiological aspects of MC. We show that there are worldwide differences in the prevalence of MC, with low rates in Asian countries and higher rates in the western world. Moreover, MC is more commonly diagnosed in patients suffering from inflammatory bowel diseases or Lynch syndrome and an increased rate of MC is observed in patients with radiotherapy-induced CRCs. These findings are suggestive of a different oncogenic development. Identification of conditions that are associated with MC generates insight into the etiological pathways leading to the development of this special subtype.

Colorectal adenocarcinoma as a second malignant neoplasm following Wilms' tumor and rhabdomyosarcoma

Colorectal carcinoma is one of the most common primary malignancies in adults and occurs in older patients after pelvic radiation. It is rare in children and young adults. We report two cases of colonic adenocarcinoma which were second malignant neoplasms following treatment for early childhood malignancies. One child had Wilms' tumor at 9 months of age treated with preoperative radiation and surgery. He developed radiation colitis and multifocal intestinal adenocarcinomas 42 years later and died with abdominal carcinomatosis. The second child had retroperitoneal embryonal rhabdomyosarcoma at age 1 year and was treated with preoperative radiation, surgery, and chemotherapy. At age 2 years he had radiation colitis; at age 11 years he had rectal adenocarcinoma associated with adenomatous polyps, focal adenomatous change and radiation colitis. Immunohistochemical studies revealed p53 positivity in both adenocarcinomas and in adenomas from the second patient, suggesting that p53 mutation was involved in carcinogenesis. The history of high-dose radiation in early childhood and the multifocal lesions suggest the adenocarcinomas in both patients were second malignant neoplasms, with associated reactive and benign neoplastic and premalignant lesions well documented in one case. These two cases document the phenomenon of early onset of adult type tumors in survivors of childhood cancer and emphasize the need for continued clinical evaluation of patients at risk for second malignant neoplasms.

Clinicopathologic characteristics of large bowel cancer developing after radiotherapy for uterine cervical cancer

PURPOSE

This study was designed to clarify the characteristics of large bowel cancer developing after radiotherapy for uterine cervical cancer.

METHODS

A retrospective chart review was performed.

RESULTS

The latent period was a mean of 20.5 years. The most common site was in the rectum (16/32). Mucin-producing carcinoma was observed in 53.1 percent, with an especially high rate of 75 percent in the rectum. Histologic radiation damage was also demonstrated at a high rate of 64.3 percent.

CONCLUSIONS

It was difficult to judge from clinicopathologic findings whether large bowel cancer developed with relation to radiation effect. We emphasize, however, that the characteristics are different from ordinary large bowel cancer. Particular consideration should be given to the high incidence of mucin-producing carcinoma.

Radiation injuries of the colon and rectum

Approximately 5% to 10% of patients receiving abdominopelvic radiation therapy will develop a colon or rectal injury. Thorough evaluation of the patient to determine the extent of the injury and the presence of concomitant lesions and to rule out recurrent malignancy is urged. Many radiation complications can be managed with medical regimens. Although colostomy remains a valuable and frequently utilized mode of treatment, it is by no means the sole alternative when surgical intervention is required. Rectal resection with colorectal or coloanal anastomosis can be performed safely for some injuries involving the distal rectum. Surgery for irradiated bowel should be focused on minimizing dissection to minimize injuries and on providing healthy non-irradiated tissues to provide adequate blood supply to promote healing. Patients who have received abdominopelvic radiation are at greater risk of developing colorectal cancer, and cancer surveillance should be commenced 5 years after completion of therapy.

Late cytokinetic abnormalities in irradiated rectal mucosa

Late cytokinetic changes of the colonic crypt epithelium after radiation therapy were investigated. A monoclonal antibody to bromodeoxyuridine (anti-BrdU MAb) was used in tissue specimens previously incubated with BrdU to show S-phase cells by immunohistochemical technique. Endoscopic rectal biopsies were taken from 30 patients previously treated with radiotherapy for gynaecological cancer and from 50 patients with comparable but untreated neoplasms, as controls. Number and height distribution of S-phase cells were evaluated by dividing each crypt column into 5 equal longitudinal compartments. No statistically significant differences were found in total Labelling Index (LI) between controls and irradiated mucosa, whereas LI per crypt compartment, percentage of labelled compartments and percentage of BrdU-positive cells in the middle and superficial portions of the crypt were significantly higher in patients submitted to radiation therapy. This kinetic abnormality corresponds to a progressive shift of the major zone of DNA synthesis to the upper third of the crypt as a late reaction to radiation and represents an early step in the histogenesis of colorectal cancer. These results lend support to the view that there is a higher risk of colorectal carcinoma after pelvic irradiation.

Colon and anorectal cancer after pelvic irradiation

Seventy-six cases of colon or anorectal cancer after pelvic irradiation for other malignant or benign lesions were reviewed. The patients were 13 men and 63 women with a mean age of 65 years; 67 percent had received irradiation for gynecologic malignancy. The cancer developed at a mean of 15.2 years after irradiation (peak frequency between five and ten years); 85 percent of the patients had a mild to prominent radiation reaction around the cancer. Of the 72 adenocarcinomas, 26 percent were mucinous. Only 17 percent of patients presented with symptoms of radiation proctitis, and the mean radiation dosages were not high. High radiation dosage and severe radiation damage may not be essential for radiation-associated colorectal cancer. The overall five-year survival rate was 48 percent. Close surveillance of the colon and anorectal regions of these high-risk patients at five years after irradiation is indicated.

Carcinoma of the large bowel after a single massive dose of radiation in healthy teenagers

Three healthy teenagers were exposed to a single pelvic x-ray irradiation as part of sterilization experiments performed in the Auschwitz concentration camp in 1943. Single and multiple carcinomas of the colon and rectum developed 40 years later in the radiation field. Histologic examination of surgical specimens revealed severe radiation-induced changes in all layers of tumor-adjacent areas. In contrast to previous reports of radiation-induced large bowel cancers, these women had not undergone repeated courses of radiation, had no known co-existing disease that might raise the risk for colonic and rectal malignancies, and had an extremely long and remarkably similar latency period. These cases emphasize the need for long-term surveillance in previously radiated patients. Since thousands of teenagers were subjected to similar sterilization experiments, awareness of this association might help in the early diagnosis of additional cases.

Surgical treatment of radiation injuries of the colon and rectum

Between 1950 and 1983, radiation-induced proctitis was diagnosed proctoscopically in 720 patients at the Mayo Clinic. Sixty-two patients with severe colorectal symptoms were treated surgically. The interval from cessation of radiotherapy to onset of symptoms ranged from 3 weeks to 24 months (mean 33 months). The 62 patients underwent a total of 143 operations with 8 operative deaths (13 percent), and 40 patients (65 percent) had 61 complications. The morbidity rate was lower after colostomy alone (44 percent in 27 patients) than after more aggressive operations (80 percent in 35 patients). Transverse loop colostomy and descending colostomy were safer than sigmoid colostomy. The dissection adhesions, opening of tissue planes, and careless manipulation of intestine may result in necrosis and perforation of the intestine, bladder, or vaginal wall; these were the main causes of fecal and other internal fistulas in our study.

Adenocarcinoma and colitis cystica profunda in a radiation-induced colonic stricture

A case of adenocarcinoma of the rectum occurring 17 years after pelvic irradiation for squamous carcinoma of the cervix is reported. Earlier colonic resection had shown localized colitis cystica profunda in a radiation-induced colonic stricture. Colorectal cancer is an infrequent sequel to radiotherapy, which may occur many years after treatment of the primary tumor. Prolonged follow-up of these patients is essential.

Radiation-induced esophageal carcinoma

Radiation-induced carcinoma of the esophagus is rare and only 8 cases have been reported since 1957. This article presents 2 additional patients in whom esophageal carcinoma developed in segments previously exposed to large therapeutic doses of irradiation. The first patient had received 5,000 rads to her mediastinum and the second patient 3,200 rads to her neck region. The latent intervals were 11 years and 30 years, respectively.