Lasers: reflections on their evolution.

A review of the past 22 years of laser applications shows that a great deal of progress has been made. It allows one to see the evolution of laser therapy, compare it with other modalities used in surgical oncology, and identify certain program that merit clinical trial. Use of lasers in surgical oncology began with a laser knife. Tissues were divided and removed with the focused beam of the CO2 laser, which replaced the scalpel previously used to perform surgical procedures. Later, the Nd:YAG laser was used in hollow visci such as the trachea and esophagus to open obstructed passages and possibly to cure many cancers. The operating microscope was used in the larynx to remove benign and malignant lesions, and for obstructing lesions to provide time to treat medical complications by reopening airway passages, and to add irradiation and/or chemotherapy preoperatively. Many times the Nd:YAG laser was used gastroscopically to treat bleeding or obstruction. Cytoreduction by laser made surgery or chemotherapy, or both, plausible. Addition of the sapphire tip and, later, the bare of sculptured fiber increased the variety of procedures possible with the Nd:YAG laser. Photodynamic therapy (PDT) uses various drugs that are localized in cancer cells. The cancer is then destroyed by laser emissions of the proper wavelength. One of the problems with PDT is getting the light to the tumor. Preactivation is addressed in this report. The problems associated with anaerobic tumors are discussed and suggestions for clinical trials offered. Laser hyperthermia is compared with induced hyperthermia as well as in combination with irradiation. Protocols of local laser hyperthermia combined with irradiation need further exploration. This review addresses the use of lasers in the destruction of tumor cells for bone marrow transplant and several old and new experiments used to block the AIDS virus. Finally, ongoing research is discussed, including the present and future roles of lasers.

Soft tissue studies with 805 nm diode laser radiation: thermal effects with contact tips and comparison with effects of 1064 nm Nd:YAG laser radiation.

This study compares the perioperative depths of thermal coagulation, charring, and incision in rabbit liver, internal anterior abdominal wall skeletal muscle, and abdominal skin and in swine liver and abdominal skin obtained with 805 nm diode laser and 1,064 nm Nd:YAG laser radiation using 300-microns-diameter conical-tip and 1,200-microns-diameter spherical-tip contact fibers by hand. Additionally, the total depth of tissue necrosis surrounding incisions made with both lasers and contact tips is determined 48 hours postoperatively in the three tissues, and healing of the liver and abdominal wall muscle 21 and 35 days postoperatively is assessed histologically. Perioperatively determined charring, coagulation, and incision depth obtained in all tissues with either 805 nm or 1,064 nm laser radiation were sensibly equivalent at equal laser power values for each of the two contact tip shapes tested. At equal laser power values, coagulation depths obtained in rabbit abdominal skin using the 300-microns-diameter conical tip differed significantly (P < or = 0.01) from those values obtained with the 1,200-microns-diameter spherical tip. Incision depths obtained with the two different contact tip shapes at equal laser power settings in the different tissues studied differed in a few instances with no apparent pattern relating to tissue type or laser power. Depth of incisions obtained with both laser and tip types increases in the range of 6-12 w, but plateaus in the range 12-18 w in the tissues studied. Incisions obtained with both diode and Nd:YAG laser contact were essentially hemostatic, with self-limiting oozing at most.(ABSTRACT TRUNCATED AT 250 WORDS)

Preactivation: a new concept for generation of photoproducts for potential therapeutic applications.

Controlled exposure of photoactive compounds to light prior to their use in biological targets results in the formation of heretofore unknown photoproducts. This process of photoproduct generation, termed preactivation, renders the photoactive compound capable of systemic use without further dependence on light. We have demonstrated that preactivated Merocyanine and preactivated Photofrin-II possess significant antitumor and antiviral activity against certain tumor cells and viruses, while under identical conditions normal cells and tissues are minimally affected. Thus, the preactivation procedure may represent a promising therapeutic modality for controlling systemic malignancies and viral infections.

Thermal effects in tissues from combined simultaneous coaxial CO2 and Nd:YAG laser beams.

This study examines the depth of thermal coagulation and charring in swine liver, kidney cortex, tongue (inferior surface), skeletal muscle, inflated lung, and skin resulting from in vivo incision with simultaneous coaxial CO2 and Nd:YAG (1.064 microM) laser beams. At values of 20 w and 40 w, respectively, and at values of 30 w and 60 w, respectively, of combined CO2 and Nd:YAG laser radiation, coagulation depths determined histologically in liver were significantly greater (P less than 0.01) than in the other tissues and were significantly less in inflated lung (P less than 0.05) than in other tissues for the larger laser power settings employed. Coagulation depths achieved at 10 w and 20 w, respectively, and at 20 w and 40 w, respectively, of CO2 and Nd:YAG laser power were comparable to those obtained by other workers in liver and other relatively vascular tissues using a contact Nd:YAG laser tip. Charring depths obtained at power settings of 30 w (CO2) and 60 w (Nd:YAG) were greater in liver (P less than 0.001) than in all other tissues examined. Hemostasis during incision was achieved only for values of the ratio of CO2 to Nd:YAG laser power in the range 2-3 in the more vascular tissues, liver and kidney cortex, whereas hemostasis was achieved also in the lesser vascular tissues at higher values. These results strongly suggest the usefulness of combined simultaneous CO2 and Nd:YAG laser beams in surgery of the more vascular organs and tissues.

Nasal and nasopharyngeal paraganglioma.

Paragangliomas of the nasal cavity and nasopharynx should be classified according to the presumed origin from the nasal, jugulotympanic, vagal, or ciliary paraganglion because of the substantial differences in clinical behavior and operative management. This paper presents the ninth published case of a primary nasal paraganglioma and reviews the previously reported cases. Primary nasal paragangliomas are generally localized, although the potential for local invasion is well documented. Malignancy or functional activity has not been described. Complete excision is curative. Jugulotympanic, vagal, and ciliary paragangliomas with extension into the nasopharynx or nasal cavity are typically more advanced at the time of diagnosis and require complete evaluation by computed tomography and arteriography to determine the tumor extent. The operative approach is dependant on the extent of tumor invasion. Irradiation and tumor embolization have been useful for unresectable or partially excised tumors.

State of the art of lasers in oncologic surgery.

The laser first described by Shawlow and Townes in 1957 was built by Ted Maiman in 1960. Many forms of lasers rapidly evolved using solids, liquids, and gasses from the medium. Applications in many fields grew rapidly; medicine has been in the forefront. Many branches of medicine found applications in surgical oncology, pulmonary, dermatology, vascular surgery, and, now, infectious diseases using this modality. This paper discusses part of the benefits for research and treatment of cancer.

Lasers in cutaneous disease.

One of the first clinical uses of the laser was in dermatology. It was used to help in diagnosing not only the presence of disease but the extent. It was used in various large naevi and very soon in port wine stains and other vascular anomalies. Skin cancer soon was treated with the laser, and soon tumors in patients with various platelet defects could be resected successfully with a minimal risk. The advent of photodynamic therapy now allows successful treatment of many lesions.

Laser surgery in the treatment of cancer.

Research on the medical applications of the free electron laser is being carried out in several institutions, including our own. The initial studies point to many new wavelengths and a higher output of the various wavelengths that are presently being used. The search continues for chromophores that may be administered orally or intravenously that will concentrate in tumors. Thus, medical laser technology, just over 25-years-old, is expanding rapidly. Research will doubtless lead to its increased refinement and to improved patient care in the future.

Lasers in plastic and general surgery.

Physicians have worked with basic scientists to develop lasers suitable for surgical applications. Because the use of lasers offers improved coagulation and reduced bleeding, applications in surgery have developed rapidly. Plastic surgery and dermatology have realized important advances with the development of laser surgery. The argon laser is commonly used in plastic surgery; the carbon dioxide laser is useful in treating patients with complications such as infections or clotting abnormalities. The CO2 laser is important in cancer surgery, as an adjuvant to liver surgery, and in pancreatic surgery. Photoradiation is an exciting new area of laser use being developed.

The histology of liver tumors in oral contraceptive users observed during a national survey by the American College of Surgeons Commission on Cancer.

As part of the national survey on the tumorigenesis of oral contraceptive drugs conducted by the American College of Surgeons' Commission on Cancer, a histologic study was made of 94 cases of liver tumors in users and non-users of oral contraceptives. Pathologic criteria were established and then the slides were studied; the results were tabulated to determine the significance of each of the criteria as related to the use of contraceptives. These criteria included tumor size, peliosis hepatis, hemorrhage, necrosis, fibrosis, thrombosis, and vascular alterations of the intima and media. Cases of focal nodular hyperplasia in pill users exhibited greater vascular alterations, fibrosis, peliosis, and tumor size as compared to focal nodular hyperplasia observed in non-pill users. In addition, hemorrhage, necrosis, and peliosis were much more common in hepatic cell adenoma than in focal nodular hyperplasia. In the material reported in this series there were no hepatic cell adenoma cases observed in non-pill users. Focal nodular hyperplasia cases exhibited an overwhelmingly greater degree of vascular intimal and medial alterations than hepatic cell adenoma. The results suggest that the effects of oral contraceptives on the liver may be primarily upon the vasculature.

Survey of primary liver tumors and oral contraceptive use.

The American College of Surgeons' survey data on 378 female and 165 male cases of primary liver tumors reported by 477 hospitals in the United States during 1970--1975 are presented. In males, 91.5% of the tumors were malignant, confirming the rarity of benign liver tumors in males. Among females, 43.9% were malignant and 56.1% were benign. Of the 212 benign tumors, 96 were hepatic cell adenomas and 58 were focal nodular hyperplasias. A positive history of oral contraceptive use was found in nearly half of all tumors, 65% of benign tumors, 74% of hepatic cell adenomas, and 74% of focal nodular hyperplasias. High frequencies of benign tumors were observed in the age group 20--30 yr. More than 80% of the tumors in this age group were found in oral contraceptive users. Symptomatology was more severe among users. No case of intraperitoneal bleeding was observed in nonusers. The findings confirm the suggested association between use of oral contraceptives and hepatic cell adenomas and focal nodular hyperplasias.

PIP: The American College of Surgeons conducted a survey of primary liver tumors in cancer-approved hospitals throughout the U.S. in the 6-year period, 1970-75. Of the 165 male cases identified, 91.5% were malignant, indicating the rarity of benign liver tumors in males. Of the 378 female cases located, 43.9% were malignant and 56.1% were benign. Nearly 50% of all primary liver tumors were found in women with a positive history of OC (oral contraceptive) usage, with OC history unknown in 29% of the study population. OC users accounted for 65% of all benign tumors reported, 74% of all hepatic cell adenomas, 74% of all focal nodular hyperplasias, 80% of benign tumors in the 20-30 year age group, and almost 90% of hepatic cell adenomas in the age group 26-30. This incidence survey confirms the reported association between OC usage and some types of benign liver tumors, especially hepatic cell adenomas and focal nodular hyperplasias. It is pointed out, and illustrated with graphs, that the age pattern for benign tumores corresponds to the age pattern for OC use. More of the OC users who developed benign tumors had used mestranol, results confirming earlier reported associations. However, this may simply be due to the fact of mestranol's earlier availability. Symptomatology, particularly with regard to pain and mass, was more pronounced in OC users. Results on duration of OC use and any association with tumor development were inconclusive. The incidence of benign liver tumors has increased from 1970 to 1975.

Management and survival of carcinoma of the colon: results of a national survey by the American College of Surgeons.

Survey results of long- and short-term outcome audits of colon cancer in participating hospitals with cancer programs conducted during 1976-7 by the American College of Surgeons are presented. In the long-term audit of 38,621 cases reported by 327 hospitals in 46 states, the overall percentage of cases in localized stage (29.3%) is significantly lower than in the recent series from the National Cancer Institute. The observed survival was substantially lower than the survival rates published in recent smaller series; however, survival approaches the end results for the period 1967-1973. In the short-term audit, the analysis of 11,655 cases diagnosed in 1976 and reported by 491 hospitals from fifty states showed that while 41% of patients had symptoms for less than a month, only 29.5% were diagnosed in the localized stage. Surgery was the predominant treatment modality with an overall resectable rate of 83%. No difference was observed in the stage at diagnosis when the short-term audit (1976) was compared with that found in the long-term audit (1971). The results suggest that the early diagnosis of symptomatic patients may not always substantially improve the cure and survival rate. The screening of asymptomatic patients is suggested as the more promising approach to the substantial improvement of presently less than ideal end results.