     The summaries of the Colorado Court of Appeals published opinions
  constitute no part of the opinion of the division but have been prepared by
  the division for the convenience of the reader. The summaries may not be
    cited or relied upon as they are not the official language of the division.
  Any discrepancy between the language in the summary and in the opinion
           should be resolved in favor of the language in the opinion.


                                                                   SUMMARY
                                                                June 28, 2018

                                2018COA93

No. 17CA1936, City of Boulder v. ICAO — Labor and Industry —
Workers’ Compensation — Coverage for Occupational Diseases
Contracted by Firefighters

     A division of the court of appeals considers whether a

firefighter’s cancer risks must be ranked in a workers’

compensation case, and if so, whether the highest risk must be

considered the cause of a firefighter’s cancer, to the exclusion of all

other causes. The division concludes that a trio of Colorado

Supreme Court cases — City of Littleton v. Industrial Claim Appeals

Office, 2016 CO 25; Industrial Claim Appeals Office v. Town of

Castle Rock, 2016 CO 26; and City of Englewood v. Harrell, 2016

CO 27 — do not require administrative law judges to rank risk

factors in the course of determining whether employers have
rebutted the statutory presumption found in section 8-41-209,

C.R.S. 2017.

     The division also concludes that there was substantial

evidence to support the judge’s factual findings that the employer

had not overcome the presumption of compensability.
COLORADO COURT OF APPEALS                                        2018COA93


Court of Appeals No. 17CA1936
Industrial Claim Appeals Office of the State of Colorado
WC No. 4-990-597


City of Boulder Fire Department and CCMSI,

Petitioners,

v.

Industrial Claim Appeals Office of the State of Colorado and Dean Pacello,

Respondents.


                              ORDER AFFIRMED

                                 Division I
                        Opinion by JUDGE BERNARD
                      Taubman and Welling, JJ., concur

                          Announced June 28, 2018


Dworkin, Chambers, Williams, York, Benson, & Evans, P.C., David J. Dworkin,
Denver, Colorado, for Petitioners

No Appearance for Respondent Industrial Claim Appeals Office

Law Office of O’Toole and Sbarbaro, P.C., Neil D. O’Toole, Denver, Colorado, for
Respondent Dean Pacello
¶1    Must a firefighter’s cancer risks be ranked in a workers’

 compensation case, and, if so, must the highest risk be considered

 the cause of the firefighter’s cancer, to the exclusion of other

 causes? We answer these questions in the context of a challenge to

 the final order of a panel of the Industrial Claim Appeals Office of

 Colorado that affirmed the decision of an administrative law judge.

 The challengers are an employer, the City of Boulder Fire

 Department, and its insurer, Cannon Cochran Management

 Service, Inc., or CCMSI, which we shall refer to both as “the City.”

 The judge found that the City had not overcome the statutory

 presumption that the squamous cell carcinoma in firefighter Dean

 Pacello’s tongue was compensable.

¶2    The City contends that the judge should have ranked the

 possible causes of the firefighter’s cancer to identify the highest risk

 factor. When the judge did not do so, the City continues, he did not

 follow a trio of Colorado Supreme Court opinions that had

 interpreted section 8-41-209, C.R.S. 2017, which we will shorten to

 “section 209,” and its statutory presumption. We disagree because

 we conclude that (1) the trio of cases does not require the judge to

 rank the causes of the firefighter’s cancer; (2) the sufficiency of the


                                    1
 evidence that the City needed to overcome section 209’s

 presumption of compensability was a question for the judge to

 decide; and (3) substantial evidence supported the judge’s factual

 findings. We therefore affirm the panel’s decision.

                I. Background and Procedural History

¶3    The firefighter worked for the City’s fire department for thirty-

 five years. He retired in 2013. In July 2015, a doctor discovered

 that the firefighter had squamous cell carcinoma in his tongue. He

 filed a claim for workers’ compensation benefits under section 209.

¶4    The legislature enacted section 209 in 2007. Ch. 245, sec. 1,

 § 8-41-209, 2007 Colo. Sess. Laws 962-63. Subsections (1) and

 (2)(a) of section 209 create a presumption that brain, skin,

 digestive, hematological, or genitourinary cancers are compensable

 if stricken firefighters meet certain criteria. But the legislature did

 not impose strict liability for these cancers on fire departments or

 cities. Instead, under section 209(2)(b), an employer, such as the

 City, may overcome the presumption by showing that a firefighter’s

 cancer “did not occur on the job.”

¶5    The City challenged the firefighter’s workers’ compensation

 claim. It maintained that the human papillomavirus 16/18, which


                                      2
 is a sexually transmitted virus known to cause cancer of the tongue

 in some men, was the more likely cause of his cancer. (A biopsy

 determined that the mass at the base of the firefighter’s tongue was

 positive for the virus.)

¶6    To overcome the statutory presumption of compensability, the

 City retained a medical expert, Dr. Richard Bell, who specialized in

 cancers of the head and neck. Dr. Bell testified that, because the

 firefighter’s tumor tested positive for the virus, “and the association

 between [the virus] and [cancer caused by the virus] and cigarette

 smoking is . . . weak,” the firefighter’s tongue cancer “was not

 related to his occupation . . . .” Dr. Bell added that the

 “preponderance of the evidence would suggest that [the firefighter’s

 cancer] [had been] caused by a virus that was sexually transmitted

 that was not related to occupational smoke exposure.”

¶7    Dr. Alexander Jacobs, an internal medicine specialist, echoed

 Dr. Bell’s opinion. Dr. Jacobs observed that

            [t]his is one of the few instances where we
            actually have a known etiologic factor that
            causes cancer. In women, this is in the form
            of cervical cancer and in both men and women
            in the form of oral/pharyngeal cancer.




                                    3
           In conclusion, [the firefighter] does have
           metastatic squamous cell carcinoma of the
           tongue and oral pharynx. Surgical pathology
           was positive for [the virus]. In my opinion,
           tobacco usage and even alcohol usage may
           have added a predisposition to this condition.
           However, the cause is clearly the . . . virus.

¶8    In response, the firefighter offered testimony from Dr. Annyce

 Mayer, an occupational medicine expert, to refute the opinions of

 Drs. Bell and Jacobs. Dr. Mayer testified that, in her opinion, the

 firefighter’s cancer was caused by a “combination of [the virus] and

 the carcinogens to which he was exposed . . . that significantly

 elevated his risk of developing the cancer.” She added that “we do

 know that the risk is significantly increased with the combination of

 the two.” She cited a 1998 study in support of her opinion. It

 found a “1.7-fold increased risk” of contracting cancer from the

 virus alone; a “3.2-fold increased risk” from smoking alone; but “a

 synergistically-increased risk of 8.5-fold in those with both [the

 virus] and smoking.” She thought that, although the 1998 study

 examined cigarette smoking rather than exposure to smoke while

 fighting fires, it was nonetheless relevant because “cigarette

 smoking and carcinogen exposures in fire, soot, and smoke have

 some carcinogens in common.”


                                    4
¶9     The firefighter’s treating doctor, Dr. Sander Orent,

  corroborated Dr. Mayer’s opinions. He described the firefighter’s

  cancer as a “multifactorial disease” that was

            a result of not just the exposure to carcinogens
            or the presence of [the virus]. It is a product of
            the fact that the necessary soil for cancer is
            the [virus] and the carcinogen. Something has
            to make the seed grow. The [virus] is sitting
            there doing nothing until the carcinogen comes
            along and suppresses the immune system to
            the point where the malignancy develops.

            We know that there are multiple causes of
            immunosuppression in firefighters.

            [The firefighter] has been exposed to
            uncounted amounts of toxins in the course
            and scope of his job. . . . [T]he preponderance
            of the evidence, in my view, is overwhelming
            that his exposures to carcinogens in the
            course and scope of his work are far more
            important than any other factor in activating
            that [virus] that was there.

  He added that the firefighter had been “absolutely” exposed to the

  triggering carcinogens “on the job.”

¶ 10   Dr. Bell, who the reader will recall was one of the City’s

  experts, rejected Dr. Orent’s assessment. Dr. Bell observed that

  “there’s simply no data, whatsoever, specifically with regard to [the

  virus] and occupational smoke exposure.” Because the majority of



                                    5
  virus-related cancers occur in nonsmokers, Dr. Bell disagreed that

  smoking is a necessary catalyst for the disease’s development. He

  instead concluded that “[i]t’s not necessary to have a significant

  smoking history to . . . develop [virus]-related head and neck

  cancer.” He reiterated that, without the virus, the firefighter “would

  not have had this particular [virus]-related cancer.” But he

  conceded that he could not dispute “the fact that smoking may or

  may not increase the risk of developing [the viral] infection and

  [virus]-related cancer.” He did not know “anything about

  firefighting.”

¶ 11    Based on this evidence, the judge decided that the firefighter’s

  cancer was compensable and awarded him benefits. The judge

  thought that Dr. Mayer’s testimony that it had been “the

  combination of [the virus] and [the firefighter’s] exposure to known

  carcinogens that [had] cause[d him] to contract cancer” was more

  persuasive than the contrary testimony of Drs. Bell and Jacobs.

¶ 12    The judge agreed that the firefighter’s cancer was “related to

  the . . . virus.” But he observed that “what is less clear, is the

  relationship between [the firefighter’s] exposure to carcinogens at

  work and the development of the cancer in question.” Given this


                                     6
  uncertainty, the judge concluded that the City had failed to show

  “that it [was] more likely than not that [the firefighter’s] employment

  did not cause [his] particular cancer.”

¶ 13   The panel affirmed. It held that it would not substitute its

  judgment for the judge’s. It also determined that it was bound by

  the judge’s findings and conclusions because substantial evidence

  supported them.

¶ 14   The panel rejected the City’s argument that, by adopting Dr.

  Mayer’s and Dr. Orent’s “multifactorial” or “combination” theory of

  risk factors causing cancer, the judge had misapprehended the trio

  of supreme court cases. (The panel noted that nothing in section

  209 or in the trio of supreme court cases required an administrative

  law judge to reject a multifactorial cancer cause.) By doing so, the

  City continued, the judge had made it impossible for any employer

  to overcome the section 209 presumption because most cancers are

  not caused by a single carcinogen or exposure.

                        II. The City’s Contentions

¶ 15   The City contends that it proved that it was more likely that

  the virus had caused the firefighter’s cancer than other, more

  attenuated, risks. As a result, it carried its burden “by more than a


                                     7
  preponderance of the evidence.” It submits that, by accepting the

  “multifactorial” or “combination” of causes advanced by Drs. Mayer

  and Orent, the judge misinterpreted the trio of supreme court cases

  that had analyzed section 209:

           City of Littleton v. Industrial Claim Appeals Office, 2016
            CO 25;

           Industrial Claim Appeals Office v. Town of Castle Rock,
            2016 CO 26; and

           City of Englewood v. Harrell, 2016 CO 27.

¶ 16   According to the City, the trio of cases “requires”

  administrative law judges to “weigh and rank the risk factors to

  determine whether the employer showed by a preponderance of the

  evidence that a nonoccupational risk factor was the greater or

  higher risk factor in the firefighter’s cancer.” The judge and the

  panel therefore committed reversible error, the City continues,

  when they rested their determination that the firefighter’s cancer

  was compensable on a finding that the cause of the firefighter’s

  cancer was “multifactorial.” The City adds that, by crediting a

  multifactorial cause for cancer, the panel and the judge effectively

  rendered the section 209 presumption irrebuttable because most, if




                                    8
  not all, cancers have multiple causal risk factors. We disagree with

  all the City’s contentions.

                                III. Section 209

¶ 17   Section 209 states:

             (1) Death, disability, or impairment of health of
             a firefighter of any political subdivision who
             has completed five or more years of
             employment as a firefighter, caused by cancer
             of the brain, skin, digestive system,
             hematological system, or genitourinary system
             and resulting from his or her employment as a
             firefighter, shall be considered an occupational
             disease.

             (2) Any condition or impairment of health
             described in subsection (1) of this section:

             (a) Shall be presumed to result from a
             firefighter’s employment if, at the time of
             becoming a firefighter or thereafter, the
             firefighter underwent a physical examination
             that failed to reveal substantial evidence of
             such condition or impairment of health that
             preexisted his or her employment as a
             firefighter; and

             (b) Shall not be deemed to result from the
             firefighter’s employment if the firefighter’s
             employer or insurer shows by a preponderance
             of the medical evidence that such condition or
             impairment did not occur on the job.

  The City concedes that the firefighter’s cancer was subject to the

  section 209 presumption.


                                       9
                           IV. Governing Law

¶ 18   In 2016, the Colorado Supreme Court weighed in on the

  burden that section 209 places on employers to overcome the

  presumption.

            [W]e conclude that an employer can meet its
            burden under section [209] to show that a
            firefighter’s condition or impairment “did not
            occur on the job” by establishing, by a
            preponderance of the medical evidence, either:
            (1) that a firefighter’s known or typical
            occupational exposures are not capable of
            causing the type of cancer at issue; or (2) that
            the firefighter’s employment did not cause the
            firefighter’s particular cancer where, for
            example, the claimant firefighter was not
            exposed to the substance or substances that
            are known to cause the firefighter’s condition
            or impairment, or the medical evidence renders
            it more probable that the cause of the claimant’s
            condition or impairment was not job-related.

  City of Littleton, ¶ 49 (emphasis added).

¶ 19   In Town of Castle Rock, the supreme court further explained

  that an employer can meet its burden of overcoming the statutory

  presumption by introducing “risk factor” evidence showing that a

  firefighter’s cancer more likely arose from a nonoccupational cause.

  The court added that

            an employer can seek to meet its burden under
            section [209] to show a firefighter’s cancer “did


                                    10
             not occur on the job” by presenting
             particularized risk-factor evidence indicating
             that it is more probable that the claimant
             firefighter’s cancer arose from some source
             other than the firefighter’s employment. To
             meet its burden of proof, the employer is not
             required to prove a specific alternate cause of
             the firefighter’s cancer. Rather, the employer
             need only establish, by a preponderance of the
             medical evidence, that the firefighter’s
             employment did not cause the firefighter’s
             cancer because the firefighter’s particular risk
             factors render it more probable that the
             firefighter’s cancer arose from a source outside
             the workplace.

  Town of Castle Rock, ¶ 17.

¶ 20    But such evidence is not dispositive. Whether an employer

  has met this burden remains a question of fact for an

  administrative law judge to decide. Because the judge is the “sole

  arbiter of conflicting medical evidence . . . [the judge’s] . . . factual

  findings are binding on appeal if they are supported by substantial

  evidence or plausible inferences from the record.” City of Littleton, ¶

  51.

¶ 21    Harrell returned a case to an administrative law judge “for

  reconsideration in light of . . . City of Littleton and Town of Castle

  Rock.” Harrell, ¶ 4.




                                      11
                      V. Ranking the Risk Factors

¶ 22   The City’s contention rests on the premise that the virus was

  the primary cause of the firefighter’s cancer and that any other

  causes or risk factors were remote in comparison. The City

  maintains that, if the judge had properly applied the standards set

  out in City of Littleton and Town of Castle Rock, he would have

  concluded that it had overcome the section 209 presumption

  because the virus’s role in causing the firefighter’s cancer

  outweighed any other risks. It urges us to eschew “multifactorial”

  risks or “combination” causes in favor of a declaration that

  administrative law judges must find the one cause or risk that

  outweighs all the others. But, because City of Littleton and Town of

  Castle Rock cede discretion to administrative law judges to weigh

  the potential causes and risks, we disagree that the section 209

  presumption is automatically overcome simply by identifying a

  significant nonoccupational cancer cause.

                A. The Judge Did Not Misapply the Law

¶ 23   Despite the City’s insistence that the supreme court has

  mandated administrative law judges to rank firefighters’ cancer

  risks, the trio of supreme court cases does not express such a


                                    12
  mandate. And the trio does not preclude consideration of

  multifactorial causes of cancer. The City has not pointed us to any

  language in City of Littleton, Town of Castle Rock, or Harrell that

  requires administrative law judges to rank risks or causes, and we

  have not found any in our reading of those cases.

¶ 24   Rather, each case emphasized that an employer “can” meet its

  burden of overcoming the presumption by establishing the

  prevalence of non-work-related risk factors. See City of Littleton,

  ¶ 49; Town of Castle Rock, ¶ 17; Harrell, ¶ 2. But the trio of cases

  does not say that an employer will meet its burden by establishing

  a nonoccupational risk; the trio does not assure employers that

  they will overcome the section 209 presumption by showing that

  nonoccupational risk factors played a prominent role in the cancer’s

  development; and the trio does not state that, once employers

  introduce such evidence, they will automatically rebut the section

  209 presumption as a matter of law. In other words, the supreme

  court opened an avenue for employers to follow, but the court did

  not guarantee them that the avenue would automatically take them

  to their desired destination of rebutting the section 209

  presumption.


                                    13
¶ 25   The City’s advocacy for a requirement that administrative law

  judges rank risks or causes ignores a critical standard that the trio

  of cases announced: the determination of whether an employer has

  met its burden remains within the fact finder’s discretion. Indeed,

  City of Littleton reversed a division of this court because the division

  “erroneously failed to defer to the [administrative law judge’s]

  findings of fact, which are supported by substantial evidence in the

  record.” City of Littleton, ¶ 64. Town of Castle Rock did not simply

  set aside an order that had not considered risk-based evidence, and

  it did not hold that the risk-based evidence that the employer had

  offered had overcome the presumption. Instead, the supreme court

  remanded the case so that the administrative law judge could give

  the evidence due consideration. Town of Castle Rock, ¶ 27.

¶ 26   To hold — as the City urges — that administrative law judges

  must rank a firefighter’s various cancer risks would create the

  following rule: an employer overcomes the presumption whenever it

  presents evidence that any nonoccupational cause outweighs the

  cancer risks posed by firefighting. Such a rule would erect a nearly

  insurmountable barrier that a cancer-stricken firefighter could only

  vault by establishing that firefighting exposures outweighed all


                                     14
  other potential cancer risks. By doing so, the rule would undercut

  what the legislature wanted to do by creating the section 209

  presumption in the first place. In other words, the City’s

  interpretation would tip the scale too far in favor of employers.

¶ 27   Such a rule would also contravene the supreme court’s

  mandate that we “defer to the [administrative law judge’s] findings

  of fact” when those findings “are supported by substantial evidence

  in the record.” City of Littleton, ¶ 64. Accepting the City’s proposed

  rule would therefore deprive administrative law judges of the

  discretion that the supreme court has described, which allows them

  to consider and to weigh the evidence offered by both sides.

  Accordingly, we conclude that City of Littleton, Town of Castle Rock,

  and Harrell did not require the judge to rank the firefighter’s various

  occupational and nonoccupational cancer risks.

       B. Substantial Evidence Supported the Judge’s Findings

¶ 28   To be sure, the judge could have weighed the evidence in the

  City’s favor; but, contrary to the City’s position, the evidence did not

  mandate an outcome in its favor. Drs. Mayer and Orent testified

  that the firefighter’s cancer likely had “multifactorial” causes and a




                                    15
  combination of risk factors, amply supporting the judge’s finding of

  compensability.

¶ 29     The supreme court gave the judge the authority to determine

  whether the City had overcome the section 209 presumption. City

  of Littleton, ¶ 51. We are therefore bound by the judge’s factual

  findings if they are supported by substantial evidence in the record.

  Id. at ¶¶ 51-52. We conclude, for the following reasons, that they

  are.

¶ 30     To begin, once the judge admitted the doctors’ testimony and

  the rest of the evidence, it was up to him to decide what weight to

  give all of the evidence. Id.

¶ 31     Dr. Orent discussed the role fighting fires likely played in

  “activating” the firefighter’s cancer-causing virus. Dr. Orent

  described it as “the trigger that allowed” the virus to become

  cancerous. He emphasized that the firefighter’s lack of other risk

  factors for tongue cancer — he was a nonsmoker; he had not

  abused marijuana or drugs; he had been monogamous — meant

  that the “preponderance of his exposure virtually had to be fire.”

¶ 32     Dr. Mayer corroborated Dr. Orent’s view when she testified

  “that it was the combination of [the virus] and the carcinogens . . .


                                      16
  that significantly elevated his risk of developing cancer.” She

  backed up her opinion with a study that found “a synergistically-

  increased risk of 8.5-fold in those with both [the virus] and

  smoking.”

¶ 33   Although the City’s medical expert, Dr. Bell, thought that the

  virus, and not any carcinogens to which the firefighter had been

  exposed on the job, had caused his cancer, Dr. Bell did not entirely

  dispute Dr. Mayer’s synergistic theory. Instead, he called it a

  “grayer area,” and he noted that “older data” existed that suggested

  “there may be an association” between the virus and firefighting

  exposures.

¶ 34   This evidence sufficiently supports the judge’s finding and

  conclusion that the City had failed to show that it was “more likely

  than not that [the firefighter’s] employment [had] not cause[d] [his]

  particular cancer.” We, like the panel, are therefore bound by the

  judge’s decision. City of Littleton, ¶¶ 51-52.

¶ 35   In reaching his decision, the judge found that Dr. Mayer’s

  opinions were more persuasive than those of the City’s medical

  experts. “We must . . . defer to the [administrative law judge’s]

  credibility determinations and resolution of conflicts in the


                                    17
  evidence, including the medical evidence.” City of Loveland Police

  Dep’t v. Indus. Claim Appeals Office, 141 P.3d 943, 950 (Colo. App.

  2006). As in all workers’ compensation cases, the weight to be

  given the experts’ testimony “is a matter exclusively within the

  discretion of the [administrative law judge] as fact-finder.” Rockwell

  Int’l v. Turnbull, 802 P.2d 1182, 1183 (Colo. App. 1990). “Further,

  we may not interfere with the [administrative law judge’s] credibility

  determinations except in the extreme circumstance where the

  evidence credited is so overwhelmingly rebutted by hard, certain

  evidence that the [administrative law judge] would err as a matter of

  law in crediting it.” Arenas v. Indus. Claim Appeals Office, 8 P.3d

  558, 561 (Colo. App. 2000).

¶ 36   We conclude that the judge acted well within his discretion by

  crediting Dr. Mayer’s opinions over the contrary opinions of Drs.

  Bell and Jacobs. Rockwell Int’l, 802 P.2d at 1183. In the absence

  of overwhelming evidence rebutting Dr. Mayer’s and Dr. Orent’s

  opinions, we may not disturb the judge’s determination that Drs.

  Mayer and Orent were more credible and more persuasive than Drs.

  Bell and Jacobs. See Youngs v. Indus. Claim Appeals Office, 2012




                                    18
  COA 85M, ¶ 46; Arenas, 8 P.3d at 561; Rockwell Int’l, 802 P.2d at

  1183.

¶ 37   We last conclude that, because substantial evidence supported

  the judge’s factual finding that fighting fires played a causal role in

  the firefighter’s cancer, the panel did not err when it affirmed the

  judge’s decision. See City of Littleton, ¶¶ 51-52.

¶ 38   The order is affirmed.

       JUDGE TAUBMAN and JUDGE WELLING concur.




                                     19
