DOES HBO REDUCE CANCER RECURRENCE
IN IRRADIATED PATIENTS?
The National Cancer Institute issued a consensus statement in 1990 stating that osteoradionecrosis can be prevented but when present is best managed by hyperbaric oxygen (HBO) alone, or with surgery.1 Late radiation tissue injury is a progressive, obliterative endarteritis which results in a hypoxic, hypovascular, hypocellular tissue bed.2 These changes make healing after surgical procedures difficult or impossible. This has led to the development of the "Marx Protocol", which induces neovascularization and healing in these damaged tissues and has been proven clincally effective and cost-effective.
Marx previously reported the 5 year recurrence rate of squamous cell carcinoma in 405 patients followed from 1985-1991.2 Of these patients, 245 received HBO under a protocol for reconstructive surgery, or for mandibular osteoradionecrosis. All were staged using the Joint Commission of Cancer Staging TNM classification system.
FIVE YEAR CANCER RECURRENCE RATES
Stage Non-HBO Recurred HBO Recurred
I 296 (21%) 36 6 (16%)
II 58 (24%) 94 17 (18%)
III 50 6 (32%) 92 19 (21%)
IV 23 9 (38%) 23 6 (28%)
The results reveal a reduced incidence of recurrence in every stage of squamous cell carcinoma in those who have been exposed to HBO.(Table 1) These differences, though statistically significant, were small, and Marx was quick to point out that while HBO may have a chemoprotective effect, it is also possible that the greater radiation dose was applied to those who required HBO and thus one would anticipate better tumor control.
A recent prospective study followed 46 cancer patients for 3 years who were exposed to a minimum of 30 hours of HBO.3 This study population was compared to a study-group matched for tumor type, age, sex, stage and year of treatment.
CANCER RECURRENCE RATES
CONTROLS HBO GROUP
Tumor type # Recur. Rate # Recurr. Rate
Gingiva 10 2 10 1
Maxilla 7 3 7 0
Floor of mouth 7 2 7 0
Salivary gland 7 3 7 3
Tonsil 5 1 5 0
Oral tongue 4 1 4 0
Ear cana 3 0 3 0
Thyroid 2 0 2 0
Eye 2 0 2 0
Nose 1 0 1 0
Epipharynx 1 0 1 0
Totals 49 12 (24.5%) 49 4 (8.2%)
Review of this data (Table 2) shows a reduced incidence of cancer recurrence in the HBO group when compared to a matched control group.
Of note is the fact that the matched control group was not statistically different from a larger control group consisting of all 1175 cancer patients treated by the ENT Division of the author's institution, between 1988 and 1992.
Additional review of data indicated that within the HBO-treated group of patients, there were fewer than expected recurrences of maxillary carcinomas, gingival carcinoma, floor of the mouth carcinomas and tongue carcinomas. Only in the recurrence rate of adenoidcystic carcinomas of the salivary glands was there a comparable number between the HBO and non-HBO treated groups.
The preponderance of available literature now suggests that HBO is not cancer causing or cancer promoting.4 Work by both Marx and Granstrom has provided another provocative conflict that requires further clinical research - namely: can HBO be considered chemoprotective against cancer recurrence. Time (and research) will tell.
1.National Cancer Institute: Monograph 1990: No. 9 Consensus Development Conference on Oral Complications of Cancer Therapies: Diagnosis, Prevention and Treatment. US Dept. HHS. National Institute of Health, Washington, D.C.
2.Marx RE:. Radiation Injury to Tissue. In: Hyperbaric Medicine Practice. Kindwall EP, Ed.. Best Publishing Co., Flagstaff (AZ) 1994;23:500-503.
3.Granstrom G: Tumor recurrence and development of new head and neck cancers after HBO treatment, a prospective clinical study. Proceedings: Int. Joint Meeting of Hyperbaric and Underwater Medicine. 1996, Milan:47-60
4.Feldmeier JJ, et al.: Does hyperbaric oxygen have a cancer causing or promoting effect? A review of the pertinent literature. Undersea and Hyperbaric Medicine 1994;21(4):467-475
Discussing patient histories is an essential part of communication and we have more science to support oxygen therapy than any other intervention in medicine. Why increasingthe inspired partial pressure a small amount over what is routinely used should be regarded as snake oil is beyond me and shows the fundamental ignorance of our profession. It is NOT quackery. There is no evidence that cancer is activated by HBO indeed the first post WW 2 use of HBO was as an adjunct to radiotherapy in which high tissue tensions increase the kill rate. There was a trial published from a London medical school about 5 years ago on the value of HBOT in glottic cancer.
Philip James MD
Wolfson Hyperbaric Medicine UnitUniversity of Dundee